Showing papers in "Soil & Tillage Research in 2017"

Recent advances in mulching materials and methods for modifying soil environment

Abstract: The global temperature has been increasing over the years due to climate change that, directly or indirectly, affects water and energy consumptions in the agriculture sector. The application of mulching practices reduces soil evaporation, conserves soil moisture, suppresses weed growth, controls soil structure and temperature, influences soil micro-organisms, and is aesthetically pleasing. This study has reviewed 189 published research papers, which described the effects of various mulching materials and methods on soil and environment that influence crop productivity. This paper describes the extent of influence of different mulching materials and methods on the hydrothermal environment of soils. It is imperative to know the processes that control soil environments under various mulching conditions and the effects of mulching materials on crop yield, productivity and water use efficiency. These issues of mulching are the prime concerns of this review study. Plastic mulching materials have a greater importance than the organic ones to control soil environment and increase crop yield. But, the organic mulching materials are inexpensive and environment friendly. The selection of an appropriate mulching material is, however, guided by crop type, crop management practices and climatic conditions. Future research is needed on the effects of low-cost biodegradable mulching materials on microclimate modifications, soil biota, soil fertility, crop growth and crop yields.

Changes in soil microbial community and organic carbon fractions under short-term straw return in a rice–wheat cropping system

Abstract: Straw return is an effective management practice for improving soil fertility and sustaining crop productivity in agro-ecosystems. A field experiment was conducted to investigate the effects of short-term (three-year) crop straw return on soil organic carbon fractions and microbial communities in a rice–wheat cropping system at three sites from central to eastern parts of China. Two treatments were established at each site: no straw return (N) and straw return (S). Compared to N treatment, S treatment significantly increased concentrations of total organic carbon (TOC, except for Qujialing site), dissolved organic C (DOC) and microbial biomass C (MBC), but did not significantly affect the easily oxidizable C content in the three sites. Soil light fraction, light fraction organic C and particulate organic C were higher for S than N treatment by 28–52% in both Guangde and Jiangyan, while these values were not significantly different between N and S treatment in Qujialing. Soil microbial community compositions of all three sites were changed with straw return. Crop straw return significantly increased total phospholipid fatty acid (PLFA), bacterial biomass and actinomycete biomass by 52, 75 and 56% in Jiangyan, but had no significant effects on PLFAs in both Qujialing and Guangde, compared to N treatment. MBC and TOC were the two main factors affecting microbial communities under short-term crop straw return. Our results demonstrated that DOC and MBC were the most sensitive indictors for assessing changes of SOC under short-term straw return in the rice–wheat cropping system, and soil properties in response to straw return were different at the three sites.

The effect of deep tillage on crop yield – What do we really know?

Abstract: The subsoil below the regularly tilled topsoil stores large nutrient stocks and can retain water even under drought conditions. Mechanical soil profile modifications, commonly referred to as deep tillage, could improve the plant availability of these subsoil resources. However, field studies on the benefits of deep tillage have delivered inconsistent findings. Therefore, we (i) conducted a meta-analysis of crop yield responses to subsoiling (loosening), deep ploughing (turning + loosening) and deep mixing of soil profiles, and (ii) reviewed the relationship between site properties, management practices, water availability and deep tillage-induced changes in yield. The meta-analysis was based on 1530 yield comparisons between deep and ordinary tillage at 67 experimental sites in mostly temperate latitudes. On average, deep tillage slightly increased yield (+6%). However, individual deep tillage effects were highly site-specific, including about 40% documented yield depression after deep tillage. At sites with root-restricting, mostly compacted soil layers, the crop yield response to deep tillage was 20% higher than at sites without such layers. In general, differences between deep tillage methods were less important than the presence of root-restricting soil layers. Soils with >70% silt (labile soil structure) showed an increased risk of negative deep tillage effects. In growing seasons with dry spells, positive deep tillage effects were greater than in average years. Topsoil fertilisation buffered both extremely positive and negative deep tillage effects. Our results suggest that deep tillage increases the plant availability of subsoil nutrients, which increases crop yield if (i) nutrients are growth-limiting and (ii) deep tillage does not come at the cost of impaired topsoil fertility. On soils with stable soil structure and root-restricting layers, deep tillage can be an effective measure to mitigate drought stress and improve the resilience of crops under climate change conditions.

Response of soil organic carbon and nitrogen stocks to soil erosion and land use types in the Loess hilly–gully region of China

Abstract: Erosion influences the vertical and horizontal distribution patterns of soil and soil organic carbon (SOC) at a landscape scale. To further understand the effect of erosion on SOC and total soil nitrogen (TSN) stocks in relation to land use types after the implementation of the “Grain for Green” program in the Loess hill-gully region, the SOC, TSN, and Caesium-137 ( 137 Cs) contents were analyzed at three selected landscape positions under three land-use types: artificial grassland (AGL), native grassland (NGL) and artificial plantation of Robinia pseudoacacia (AFL). The results showed that all land uses experienced considerable net erosion since the mid-1950s, with an average total loss depth of 2.05 cm for AFL, 1.49 cm for AGL, and 0.54 cm for NGL. The SOC stocks in AFL and NGL were 72.3% and 26.2% lower, respectively, than that in AGL in the 0–100 cm soil layer, and significant positive correlation between SOC and TSN stocks on each layer in the soil profile was observed (R 2 > 0.90). The result showed that compared with other land-use types, AGL had a greater SOC and TSN sequestration capacity. The contents of SOC and TSN were positively correlated with the amount of 137 Cs in AFL and NGL (R 2 = 0.97, 0.97 for AFL, respectively, and R 2 = 0.90, 0.90 for NGL, respectively; n = 3), whereas no significant correlation was found in AGL (R 2 = 0.41, 0.01, respectively; n = 3). The results indicated that AGL was an optimal choice to mitigate soil carbon and nitrogen loss and to increase C and N sequestration in the Loess hilly–gully region. A complex process should be considered for the distribution patterns of SOC and TSN after afforestation since 1999.

Soil structure changes induced by tillage systems

Abstract: Structure represents one of the main soil physical attributes indicators. The soil porous system (SPS) is directly linked to the soil structure. Water retention, movement, root development, gas diffusion and the conditions for all soil biota are related to the SPS. Studies about the influence of tillage systems in the soil structure are important to evaluate their impact in the soil quality. This paper deals with a detailed analysis of changes in the soil structure induced by conventional (CT) and no-tillage (NT) systems. Three different soil depths were studied (0–10, 10–20 and 20–30 cm). Data of the soil water retention curve (SWRC), micromorphologic (impregnated blocks) (2D) and microtomographic (μCT) (3D) analyses were utilized to characterize the SPS. Such analyses enabled the investigation of porous system attributes such as: porosity, pore number and shape, pore size distribution, tortuosity and connectivity. Results from this study show a tri-modal pore size distribution (PSD) at depths 0–10 and 10–20 cm for the soil under CT and a bi-modal PSD for the lower layer (20–30 cm). Regarding the soil under NT, tri-modal PSDs were found at the three depths analyzed. Results based on the micromorphologic analysis (2D) showed that the greatest contribution to areal porosity (AP) is given by pores of round (R) shape for CT (52%: 0–10 cm; 50%: 10–20 cm; 67%: 20–30 cm). Contrary to the results observed for CT, the soil under NT system gave the greatest contribution to AP, for the upper (0–10 cm) and intermediate (10–20 cm) layers, due to the large complex (C) pore types. For the μCT analysis, several types of pores were identified for each soil tillage system. Small differences in the macroporosity (MAP) were observed for the 0–10 and 20–30 cm between CT and NT. A better pore connectivity was found for the 0–10 cm layer under NT.

Aggregate stability and size distribution of red soils under different land uses integrally regulated by soil organic matter, and iron and aluminum oxides

Abstract: The stability and size distribution of soil aggregates is profoundly affected by land use, but the influencing mechanisms of land use are not clear. A study was carried out to investigate and attempted to interpret the effects of land use on soil aggregates from types of land use and soil properties in soil samples and size fractions of soil aggregates. Soil samples were taken from 9 sites under paddy, forest, and upland in southern China. The wet-sieving method was used to obtain 6 size fractions of soil aggregates: >5, 5–2, 2–1, 1–0.5, 0.5–0.25, and

Cover crop effects on soils and subsequent crops in the pampas: A meta-analysis

Abstract: Fil: Alvarez, Roberto. Universidad de Buenos Aires. Facultad de Agronomia; Argentina. Consejo Nacional de Investigaciones Cientificas y Tecnicas; Argentina

Residual plastic mulch fragments effects on soil physical properties and water flow behavior in the Minqin Oasis, northwestern China

Abstract: The covering of complete plastic films on soil would affect physical and biochemical properties of the soil microenvironment. Residual plastic film fragments (RPFF), which is left behind after retrieving the most of plastic films, could affect the flow behavior in the arable layer. This study was designed to assess the potential effects of RPFF on soil physical properties, water infiltration and distribution in the soil. Treatments with and without residual plastic film fragments (RPFF and NRPFF, respectively) were performed. A dye tracer was introduced to track the water movement, and the physical properties of the soil and the dynamic behavior of water transport in the soil column of the arable layer (0–20 cm) were determined. The initial gravimetric water content, bulk density, total porosity in 0–20 cm was significantly different between RPFF and NRPFF treatment. The dark blue area in maize root and densely rooted zones under RPFF decreased by 99% and 4%, respectively, relative to that under NRPFF. The sharply changing state of infiltration and outflow indicated that water flowed along a preferential path, e.g., macro-pores in NRPFF and residual plastic film pieces in RPFF. After clearing the RPFF, the time of equilibrium in 0–5, 5–10, 10–15, and 15–20 cm soil columns decreased by 48%, 50%, 49%, and 45%, respectively. Our results highlighted that the presence of RPFF significantly influenced soil physical properties, altered soil water distribution, and decreased the matching degree of the flow distribution region and the maize root (densely rooted) zone. The present study demonstrated that the importance of clearing the RPFF for irrigation water management in agriculture produces.

Long-term effects of NPK fertilizers and organic manures on carbon stabilization and management index under rice-wheat cropping system

Abstract: The potential of storing carbon (C) in soil and offsetting the atmospheric CO 2 depends on the management practices This study investigated the long-term (15 years) effects of using nitrogen: phosphorous: potassium (NPK) fertilizers with and without organic manures namely farmyard manure (FYM), green manure (GM), and straw incorporation (SI) on soil C stabilization, and C management index (CMI) in intensive rice-wheat system in Typic Ustochrepts soil of a semiarid region in Punjab, India The long-term effects of different fertilizer treatments as control, NPK, NPK + GM, NPK + SI, and NPK + FYM on soil organic carbon (SOC), labile fractions of SOC (LFSOC), C stabilization, C sequestration, and C management index (CMI) were determined Prolonged application of NPK fertilizers alone or in combination with organic manures significantly decreased soil bulk density (from 73 to 166%) and increased total soil porosity of (from 117 to 262%) as compared to the control in surface soil (0–15 cm) Fertilizations had positive and variable effects on different LFSOC, namely water soluble C (WSC), labile carbon (LC), particulate organic C (POC), hot water soluble carbon (HWSC), and total organic carbon (TOC) Long-term intensive cultivation and fertilization significantly increased the SOC in surface soil (0–15 cm) up to 516 g kg −1 as compared with its antecedent value of 242 g kg −1 in 1999 The sensitivity index indicated that among LFSOC, LC (51–85%), WSC (67–131%), POC (64–159%), and HWSC (38–131%) were more sensitive compared with SOC (29–59%) NPK + SI (506 Mg C ha −1 ) or NPK + FYM (531 Mg C ha −1 ) along with NPK sequestered significantly higher C than the application of NPK (357 Mg C ha −1 ) or NPK + GM (410 Mg C ha −1 ) The fraction of C in stable fractions (C frac3 + C fract4 ) increased from 7 to 29% with application of NPK fertilizers and organic manures compared with that of the control The CMI indicated that the use of NPK + SI or NPK + FYM was statistically superior to the use of NPK + GM for improving the SOC status The study concluded that a relatively high sensitivity index of LFSOC may be used as an early indicator for determining the potential of different management practices for improving SOC on short-term basis The results indicated that the stability of SOC varies with the nature of the added organic manures, suggesting that the selection of organic manure is important for long-term C sequestration

Cover cropping and no-tillage improve soil health in an arid irrigated cropping system in California’s San Joaquin Valley, USA

Abstract: The concept of soil health has attracted considerable attention during the past two decades, but few studies have focused on the effects on soil health of long-term soil management in arid irrigated environments. We investigated the effects of cover cropping and no-till management on soil physical and chemical properties during a 15-year experiment in California’s San Joaquin Valley (SJV) USA. Our objective was to determine if soil health could be improved by these practices in an annual crop rotation. The impact of long-term no-tillage (NT) and cover cropping (CC) practices, alone and in combination, was measured and compared with standard tillage (ST) with and without cover crops (NO) in irrigated row crops after 15 years of management. Soil aggregation, rates of water infiltration, content of carbon, nitrogen, water extractable organic carbon (WEOC) and organic nitrogen (WEON), residue cover, and biological activity were all increased by NT and CC practices relative to STNO. However, effects varied by depth with NT increasing soil bulk density by 12% in the 0–15 cm depth and 10% in the 15–30 cm depth. Higher levels of WEOC were found in the CC surface (0–5 cm) depth in both spring and fall samplings in 2014. Surface layer (0–15 cm) WEON was higher in the CC systems for both samplings. Tillage did not affect WEON in the spring, but WEON was increased in the NT surface soil layer in the fall. Sampling depth, CC, and tillage affected 1-day soil respiration and a soil health index assessment, however the effects were seasonal, with higher levels found in the fall sampling than in the spring. Both respiration and the soil health index were increased by CC with higher levels found in the 0–5 cm depth than in the 5–15 and 15–30 cm depths. Results indicated that adoption of NT and CC in arid, irrigated cropping systems could benefit soil health by improving chemical, physical, and biological indicators of soil functions while maintaining similar crop yields as the ST system.

Chemical, organic and bio-fertilizer management practices effect on soil physicochemical property and antagonistic bacteria abundance of a cotton field: Implications for soil biological quality

Abstract: Cotton production in a long-term, consecutive, mono-cropping cotton field has greatly suffered from soil-borne diseases. In this study, a 4-year field experiment was conducted to investigate the effects of organic fertilizer (OF) or bio-fertilizer (BF) combined with a reduced chemical fertilizer (CF) on soil physicochemical properties, biological activities, antagonistic bacteria ( Bacillus, Trichoderma and Pseudomonas ) and pathogen( Fusarium and Verticillium dahliae ). Soil physicochemical and biological properties were significantly affected by different fertilization scenarios. Soil bulk density (BD) decreased by 4.69% more with 60% CF + BF treatment than with 60% CF + OF treatment. Compared with CF treatment, 60% CF + BF treatment significantly increased soil chemical properties of total nitrogen (TN), available phosphorus (AP), available potassium (AK), soil organic carbon (SOC) and dissolved organic carbon (DOC). The resistant enzymatic activities of catalase (CAT), peroxidase (POD), polyphenoloxidase (PPO) and fluorescein diacetate (FDA) were improved by the bio-fertilizer addition. The abundances of Bacillus , Trichoderma and Pseudomonas followed the order of BF > OF > CF > control. The gene copy numbers of Fusarium and Verticillium dahliae were 3.18 and 2.25 cfu × 10 3 · (g · soil) −1 with CF treatment; these decreased by 47% and 32% with 80% CF + OF treatment, respectively, and they further decreased by 86% and 46% with 80% CF + BF treatment, respectively. Together, our results demonstrated that both OF and BF significantly strengthened the enzyme activities, and the antagonistic bacterial abundance but suppressed pathogens, BF was superior to OF in regulating soil microbial abundance, particularly at a high application rate, and highlighted that SOC and AP ( P

Long-term tillage impact on soil hydraulic properties

Abstract: An improved understanding of the impact of tillage systems on soil hydraulic properties is necessary to conserve and manage soil water under a changing climate. The objective of this study was to specifically measure soil hydraulic properties (total porosity, water infiltration, saturated hydraulic conductivity, and water retention characteristics) in no-till, chisel plow, disk, and moldboard plow systems under rainfed continuous corn (Zea mays L.) after 35 yr on silty clay loam soils in eastern Nebraska. We measured ponded water infiltration (positive soil water pressure) and tension (−1 kPa matric potential) infiltration to exclude macropore (>125 μm diameter) flow. Tillage treatments affected ponded infiltration only. Moldboard plow significantly increased ponded infiltration rate by 21.6 cm h−1 at 5 min and by 8.8 cm h−1 at 60 min compared with no-till. However, when compared with disk and chisel, moldboard plow increased ponded infiltration rates at all measurements times, which lasted 3 h. Regarding cumulative infiltration, moldboard plow increased cumulative infiltration by 26.9 cm to 39.0 cm after 3 h compared with other tillage systems. Similarities in tension infiltration suggest that the higher ponded infiltration for moldboard plow was most likely due to the presence of voids or fractures (>125 μm) created by full inversion tillage. Total porosity, saturated hydraulic conductivity, and water retention among the treatments did not differ. Overall, soil hydraulic properties did not differ among tillage systems except water infiltration in these silty clay loam soils after 35 yr of management.

Assessment of spatial variability of soil properties using geospatial techniques for farm level nutrient management

Abstract: Crop productivity under rainfed farming systems in India is low due to poor water and nutrient management. The available small scale information of soil nutrients is inadequate to effectively manage individual farms held by small and marginal farmers. Large scale spatial variability assessment using grid sampling method is a feasible option to identify critical nutrient deficiency zones. The present study was conducted in a part of semi-arid tropical Deccan plateau region, India, to assess the spatial variability of soil pH, organic carbon (OC), soil available nitrogen (N), phosphorus (P), potassium (K) and sulphur (S). A total of 1508 composite samples (0–15 cm) were collected by adopting 325 × 325 m grid interval (one sample for 10 ha area) and they were analysed for soil fertility parameters. Coefficient of variation (CV) indicated that OC, N, P, K and S were high in heterogeneity (CV > 35%). Moreover, pH, P, K and S were non-normally distributed and log transformation produced normalised dataset. The semivariogram parameters (nugget to sill ratio, range and slope) indicated that the spatial distribution of soil properties were inconsistent. The spatial variability of parameters were mapped by ordinary kriging using exponential (pH and OC) and spherical (N, P, K and S) models selected based on root mean square error (RMSE) and r 2 values. Multi-nutrient deficiencies were observed in most parts of the study area and N was acutely deficient. Farm level nutrient availability status was derived from spatial variability maps and critical nutrient deficiency zones were identified. Nutrient management recommendations based on soil test results were delivered to farmers for adopting need based variable rate of fertilizer application. The generated maps can serve as an effective tool for farm managers and policy makers in site specific nutrient management.

Spatial variability of soil properties and cereal yield in a cultivated field on sandy soil

Abstract: Sandy soils are used in agriculture in different regions of the world. In Poland soils derived from sands occupy about 50% of agricultural area. Productivity of the soils depend on the soil properties that vary in the scale of field. This study aimed at determining and mapping the within-field variation of soil physical and chemical properties and grain yield of oats, rye, oats and triticale in 2001, 2002, 2003, 2015, respectively. The experiment was set up in a field (200 × 50 m) on sandy soil in Trzebieszow (region Podlasie, Poland). The soil measurements included sand, silt, clay, and organic carbon (SOC) contents, cation exchange capacity (CEC), pH in the topsoil (0–10 cm) and subsoil (30–40 cm) layers in 2001, and water content and bulk density in the topsoil layer in spring and summer 2002–2003. The yields of oats were assessed in 2001 and 2003 and those of rye and triticale in 2002 and 2015, respectively. The soil properties and cereal yields were determined at 33–55 points in a grid evenly covering the whole field area. The results were analyzed using classic statistics and geostatistics by constructing semivariograms and 2D mapping by Inverse Distance Weighting (IDW). The cereal grain yields were significantly positively correlated with the topsoil water content (SWC) (r = 0.295–0.711), clay content (r = 0.081–0.174), and SOC in the subsoil (r = 0.208–0.271) and CEC in both layers (r = 0.123–0.298) and negatively correlated with bulk density (BD) (r = –0.065 to −0.279). The spatial dependence determined by the “nugget-to-sill” ratio was moderate or weak for the silt and clay content, CEC, and pH (29–79%) and strong for SOC, BD, SWC, and crop yield (0.2–13.2%). The effective range of the spatial dependence for all studied quantities varied from 9.9 to 120 m. The cereal yields were positively and significantly correlated between all study years (r = 0.141–0.734), which indicates inter-annual similarity in their spatial distribution. The 2D maps based on the IDW allowed assessing how gradual or sharp the changes in the studied quantities from one place to another are. Similar spatial patterns of the SWC, SOC and CEC, and crop yields were observed. This is of importance in precise and sustainable field management aimed at increasing and aligning spatial crop productivity of the studied low-productivity sandy soils that will have to be used in crop production due to the current shortage of land resources and food supplies on a global scale.

Application of firefly algorithm-based support vector machines for prediction of field capacity and permanent wilting point

Abstract: Soil field capacity (FC) and permanent wilting point (PWP) are significant parameters in numerous biophysical models and agricultural activities. Although these parameters can be measured directly, their measurements are quite expensive. The purpose of this study was to develop a hybrid Support Vector Machine (SVM) combined with Firefly Algorithm (FFA) techniques (SVM-FFA) to predict the FC and PWP using some easily available soil properties. The data consist of 215 soil samples collected from different horizons of soil profiles located in the East Azerbaijan provinces, North-west of Iran. Several important parameters, including the sand,silt, clay, bulk density, and organic matter content were used as inputs, while the soil FC and PWP were the output parameters. The predictions from the SVM-FFA model were compared with SVM and artificial neural network (ANN) models. The model results were compared with regard to root mean square error (RMSE), correlation coefficient (CC) and relative root mean square error (RRMSE). A comparison of models indicated that the SVM-FFA model predicted better than SVM and ANN models with RMSE = 2.402%, CC = 0.972, RRMSE = 7.677% for FC and RMSE = 1.720%, CC = 0.969, RRMSE = 5.512% for PWP in the training data set while RMSE = 2.873%, CC = 0.962, RRMSE = 8.745% for FC and RMSE = 1.935%, CC = 0.965, RRMSE = 10.619% for PWP were obtained in the testing data set.

Response of soil water, temperature, and maize (Zea may L.) production to different plastic film mulching patterns in semi-arid areas of northwest China

Abstract: Plastic film mulching has been used widely to increase crop productivity in dryland farming. In this study, to identify the optimal mulching pattern and ensure the efficient utilization of soil water in the semi-arid areas of northwest China, we tested the following five treatments for 3 years (2013–2015): (1) full amount of plastic film with flat mulching (FL mulching) throughout the whole season (FLW), or (2) only during the growing season (FLG); (3) alternating ridges and furrows where only the ridges were mulched with plastic film (RF mulching) throughout the whole season (RFW), or (4) only during the growing season (RFG); (5) flat planting without mulching throughout the whole season (NM). The results showed that FLW was more beneficial for reducing soil water losses during the fallow season compared with RFW. FL mulching enhanced soil water consumption during the maize growing season, but promoted maize production compared with RF mulching due to the increased soil temperature. The rainfall was low during July–September in 2015, and the soil water storage at harvest under FLW and FLG were 9.13 mm higher and 8.01 mm lower than the stable soil water, respectively, thereby suggesting that FLW increased the soil water supply capacity in this drought year, and thus it was more sustainable in terms of soil water utilization compared with FLG. With FLW, the average yield increased by 838 kg ha−1, 1944 kg ha−1, 2363kg ha−1, and 5164 kg ha−1, compared with FLG, RFW, RFG, and NM, respectively, and the average net income increased by 244 USD ha−1, 520 USD ha−1, 643 USD ha−1, and 1166 USD ha−1. These results suggest that FLW was an effective method for substantially increasing economic benefits and maize yields in semi-arid areas.

Biodegradable film mulching improves soil temperature, moisture and seed yield of winter oilseed rape (Brassica napus L.)

Abstract: Biodegradable film has been proven to be a good alternative to conventional polyethylene (PE) film for crops such as maize and cotton, but its suitability for winter oilseed rape ( Brassica napus L.), one of the most important oilseed crops worldwide, has not been fully investigated. We conducted a three-year field experiment to systematically analyse and compare the effects of conventional PE film mulching (PM), biodegradable film mulching (BM), and no film mulching (CK) on soil temperature, soil water storage, water use efficiency (WUE), root growth, and yield for winter oilseed rape. The effects of increasing soil temperature and soil water storage were similar for BM and PM and were significantly higher than for CK before 150 days after sowing (DAS), but the increases of soil temperature and soil water storage were significantly lower for BM than PM after 150 DAS due to the degradation of the biofilm. The taproots of the rapeseed extended 1.7 cm significantly deeper into the soil for BM than PM, and the mass density of lateral roots in the 20–30 cm soil layer was 18–26 g m −3 significantly higher for BM at maturity stage. Evapotranspiration (ET) was significantly higher in BM than PM but still significantly lower than in CK. The average ET in BM was 10.0% higher than in PM and 10.4% lower than in CK. Yield and WUE did not differ significantly between BM and PM. Average yield and WUE in BM were 5.8 and 14.3% lower than in PM and were 38.4 and 54.5% higher than in CK. The seed content of erucic acid and glucosinolate, harmful to human health, was lower in BM than PM, while seed oil, protein, and oleic acid contents did not differ significantly between BM and PM. Biodegradable film is thus recommended as a viable option to the conventional PE film for the production of winter oilseed rape.

Temporal variability of soil management effects on soil hydrological properties, runoff and erosion at the field scale in a hillslope vineyard, North-West Italy

Abstract: Soil management in vineyard inter-rows has a great influence on soil hydraulic conductivity and bulk density, and, consequently, on runoff and soil erosion processes at the field scale. The maintenance of bare soil in vineyard inter-rows with tillage, as well as the tractor traffic, are known to expose the soil to compaction, reduction of soil water holding capacity and increase of runoff and erosion. The use of grass cover is one of the most common and effective practices in order to reduce such threats. It is therefore important to relate rainfall characteristics, soil properties and response in terms of runoff and soil erosion, from yearly to seasonal and to single event temporal scales. The objective of this work is to quantify the temporal variability of the effects of two different kind of inter-row management on soil hydrological properties, runoff and erosion in vineyards. For this reason two vineyard field-scale plots in the Alto Monferrato vine-growing area (Piedmont, NW Italy) were monitored in two years. The inter-rows were managed with conventional tillage (CT) and grass cover (GC), respectively. Fifteen series of infiltration tests were carried out during a 2-year period of observation (October 2012 to November 2014). In order to take into account the effect of tractors traffic, the tests were done on the track, and outside the track. Furthermore, a dataset of 29 rainfall-runoff events covering a wide range of topsoil characteristics was collected in the two plots, along with soil water content and runoff discharge monitoring, and determination of sediment yield in case of erosive events. An optical disdrometer installed in the plots provided also 1-min rainfall intensity data. In summer, just one month after tillage, CT soil showed very low hydraulic conductivity, so storms were able to cause Hortonian runoff and soil losses up to 5.7 Mg ha−1. In autumn and winter very high saturation-excess runoff was observed in CT, that reached 83% of the precipitation. Runoff in the grass cover plot was mainly due to saturation of the topsoil, and the annual reduction of runoff in the GC plot was about 63%. Soil erosion up to 1.2 Mg ha−1 in a single event was observed in the GC vineyard in winter. In each year of observation, most of the erosion occurred during a single event, while the total annual erosion was up to 9 times higher in the CT treatment than in the GC.

Tillage and fertilization practices affect soil aggregate stability in a Humic Cambisol of Northwest France

Abstract: Reduced tillage and organic fertilizer application usually result in an increase in soil aggregate stability (AS). However, the magnitude of the effects can vary with soil properties and season. The aim of this study was to investigate AS dynamics over three seasons in a soil under various tillage and fertilization practices. The study was performed under three tillage practices (moldboard plowing (MP), surface tillage (ST) and no-tillage (NT)) and two types of fertilizer (poultry manure and mineral) seven and eight years after their establishment in Northwest France. AS was measured in three different seasons: spring, summer and winter. Soil properties that potentially influence AS such as organic carbon (OC), hot-water extractable carbohydrates (HWEC), water content (WC) and water repellency (WR) were also studied. On average, for all sampling dates, AS was 34% higher under NT than MP. Conversely, the effect of ST on AS varied with sampling date with values close to NT in mid-spring and summer, and values close to MP in early spring and winter. Poultry manure increased AS by an average of 12% regardless of sampling date or tillage practice. Variations in AS due to management practices were related to OC (r = 0.92) and HWEC (r = 0.88). Differences in AS between sampling dates were slightly greater than the effects of management practices. On average across management practices, AS increased by 47% from early spring to summer and decreased by 59% in winter. These variations were related to soil WC (r = −0.67) and WR (r = 0.72) at time of sampling. We suggest that seasonal variations in AS were at least partly due to variations in WC which acted physically by modifying the water entry rate into the aggregates and slaking effects. In contrast, the long-term AS dynamics were related to the organic matter dynamics, which are controlled by management practices. Because of the predominant effect of climate on AS, we suggest measuring AS in winter and summer to better estimate the effects of management practices on soil erodibility in this region.

Increased cropping intensity improves crop residue inputs to the soil and aggregate-associated soil organic carbon stocks

Abstract: Many South American agroecosystems are based mainly on soybean [ Glycine max (L.) Merr.] as a sole crop in the year, which has increased concerns regarding soil conservation and ecosystems sustainability. The increase in cropping intensity (CI) has been suggested as a strategy to improve crop residue inputs, which in turn, may increase soil aggregation and soil organic C (SOC) storage, while maintaining or even increasing total sequence yields. Our objective was to evaluate the relationships between CI and crop residue input with SOC storage and soil aggregation in two contrasting northeastern Argentinean Pampas soils under no-till. Two parallel experiments were established in a Mollisol and a Vertisol evaluating six cropping sequences, starting from soybean monoculture and increasing the number of crops per year and crop diversity. Crop residue inputs to the soil (aboveground biomass, belowground biomass and total biomass), grain yield, the amount of macroaggregates (MA), SOC stored inside macroagregates (SOC MA ) and total SOC stocks were measured in both soils two years after the beginning of cropping sequences, at three soil depths. Soil organic C stocks, MA and SOC MA were all positively related with CI in both soils at 0–5 cm depth. All soil variables were lowest in simple rotations (soybean monoculture) and increased in more complex rotations (double cropping with cereals and legumes), although differences were significant (P

Buried straw layer plus plastic mulching improves soil organic carbon fractions in an arid saline soil from Northwest China

Abstract: Salt stress has been increasingly constraining crop productivity in arid lands of the world and there is some evidence that a combination of straw layer burial and plastic film mulching alleviates salt stress and increases microflora diversity in a saline soil. However, their impacts on soil organic C (SOC), especially its active fraction are not well documented. We studied the combined effects of burying straw layer and plastic mulching on SOC, microbial biomass C (MBC) and dissolved organic C (DOC) using the following four treatments: deep ploughing with no plastic film mulching (CK); deep ploughing with plastic film mulching (PM); buried maize straw layer with no mulching (SL); and buried maize straw layer plus plastic film mulching (PM + SL). Compared with CK and PM, the PM + SL and SL treatments significantly enhanced the allocation of SOC to the 20–40 cm soil layer, due to an adequate supply of organic carbon from straw incorporation; the SOC value under PM + SL significantly decreased in the topsoil (0–20 cm) after 4 years, while that under CK and SL was little altered. After 4 years, the SOC under PM + SL and SL treatments increased by 5.84 and 10.78% ( P P P P P

Multivariate assessment of soil quality indicators for crop rotation and tillage in Illinois

Abstract: The long-term implementation of crop rotation and tillage influences the soil environment through inputs and disturbance of the soil, which in turn, impact soil quality (SQ). A vital component of developing sustainable agronomic practices is to evaluate their effect on SQ. The objective of this study is to address the first step in this process by identifying soil parameters that are sensitive to changes in the soil and indicative of soil functions. Soil samples were collected from two Illinois sites with cropping systems and tillage treatments in place for more than 16 years. Crop rotation and tillage were evaluated with separate principal component analyses (PCA) of 20 soil parameters. Six principal components accounted for 74% of variability among rotations. The soil parameters loaded within these components highlighted the strong influence on carbon and nitrogen cycling indicated by greater soil organic carbon, total nitrogen, microbial biomass, and aggregate stability under crop rotations with high C:N residues and biomass production. Other strongly loaded parameters, such as soil pH and nutrient contents, are likely related to the use of nitrogenous fertilizers in grass species. Rotations with only a single contrasting crop were able to be differentiated readily while the multi-species crop rotations were only marginally able to be separated. The PCA for tillage explained 73% of variability with six principal components; of those, three were able to separate no-till from conventional tillage. As with rotation, the choice of tillage practice can have a large influence on the cycling of carbon and nitrogen, as decomposition of residues and soil organic matter are accelerated by tillage. No-till was also associated with stratification of pH and other nutrients. Soil parameters relating to carbon and nitrogen cycling have the greatest potential as SQ indicators while other measures relating to nitrogen fertilization, such as shifts in soil pH and nutrient contents, can also prove useful in comparing SQ under crop rotation and tillage in Illinois.

The role of organic/bio–fertilizer amendment on aggregate stability and organic carbon content in different aggregate scales

Abstract: This study investigated the effects of different organic and bio–fertilizer (alone or in combination) applications on aggregate stability and organic carbon (OC) content in macro (2–1 mm) and micro (0.25–0.050 mm) aggregate sizes of clay loam (Typic Xerofluvent) textured soil. In addition, correlation between OC content and aggregate stability was determined. The study was conducted as a pot experiment under greenhouse conditions and was arranged in a completely randomized design with three replications. The treatments were: control (no fertilizer) (C), inorganic fertilizer (15:15:15 compound fertilizer + ammonium nitrate, 33% N) (F), mycorrhizal fungi (Glomus spp.) (M), microalgae (Chlorella spp.) (A), bacteria (Bacillus megaterium KBA–10 + Pantoea agglomerans RK–134 + Pseudomonas fluorescens FDG–37) (BMF), bacteria (Bacillus subtilis PA1 + Paenibacillus azotofixans PA2) (BCP), vermicompost (V), vermicompost + mycorrhizal fungi (VM), vermicompost + microalgae (VA), vermicompost + bacteria (VBMF) and vermicompost + bacteria (VBCP) applied in 90 days incubation period. At the end of the 90-day incubation period, organic and bio–fertilizer amendments had an increasing impact on aggregate stability and OC content in macro– and micro– aggregate scale. Especially, bio–fertilizers in combination with vermicompost mostly had stronger effects on stability and OC content of aggregates of both size classes in comparison with control and bio–fertilizer treatments alone. In addition, significant (p

Effects of tillage practices and slope on runoff and erosion of soil from the Loess Plateau, China, subjected to simulated rainfall

Abstract: Soil erosion, particularly during summer fallow period, in sloped farmland has been identified as a critical threat to sustainable agricultural development in the Loess Plateau of China. However, the effects of varying tillage practices during the summer fallow period have not been fully investigated. The objective of this study was to determine the effects of tillage practices on runoff and sediment loss under plot (4.0 m in length and 1.0 m in width) rainfall simulations. Runoff initiation time, runoff amount, sediment loss and cumulative infiltration amount were recorded. One rainfall intensity (90 mm h −1 , 40 min), three slopes (5°, 10°, and 15°) and four prevalent tillage practices (Artificial Digging, AD; Artificial Hoeing, AH; Contour Plow, CP; and Traditional Plow, TP) were studied. Two indices, runoff reduction benefits (RRB) and sediment reduction benefits (SRB), were selected to evaluate the effect of the practice on controlling runoff and sediment. Compared to TP treatment, the AD, AH and CP were more effective in reducing the magnitude of runoff amount and sediment loss as well as increasing the rain water infiltration amount. CP with a 15° slope was an exception in which the sediment loss increased. In general, the SRB was greater than the RRB for a given tillage practice under the same slope, suggesting that the benefits from sediment reduction were more effective than the benefits from runoff reduction. RRB and SRB were the largest for AD, followed by AH and CP, irrespective of slopes. The capacity of the three tillage practices to reduce runoff and sediment decreased as the slope increased. In particular, AD at a 5° slope had the best performance in reducing runoff and sediment loss; however, SRB and RRB were −57% and 1%, respectively, for a CP plot with a 15° slope. This finding suggested that CP had a higher sediment loss and a similar runoff amount compared to those of TP. These results of plot simulated rainfall will contribute to our knowledge about the effects of different tillage practices on soil erosion from sloped farmland.

Aggregate size distribution in a biochar-amended tropical Ultisol under conventional hand-hoe tillage.

Abstract: Biochar (or pyrogenic organic matter) is increasingly proposed as a soil amendment for improving fertility, carbon sequestration and reduction of greenhouse gas emissions. However, little is known about its effects on aggregation, an important indicator of soil quality and functioning. The aim of this study was to assess the effect of Eucalyptus wood biochar (B, pyrolyzed at 550 °C, at 0 or 2.5 t ha−1), green manure (T, from Tithonia diversifolia at 0, 2.5 or 5.0 t ha−1) and mineral nitrogen (U, urea, at 0, or 120 kg N ha−1) on soil respiration, aggregate size distribution and SOC in these aggregate size fractions in a 2-year field experiment on a low-fertility Ultisol in western Kenya under conventional hand-hoe tillage. Air-dry 2-mm sieved soils were divided into four fractions by wet sieving: Large Macro-aggregates (LM; >1000 μm); Small Macro-aggregates (SM, 250–1000 μm); Micro-aggregates (M, 250–53 μm) and Silt + Clay (S + C, < 53 μm). We found that biochar alone did not affect a mean weight diameter (MWD) but combined application with either T. diversifolia (BT) or urea (BU) increased MWD by 34 ± 5.2 μm (8%) and 55 ± 5.4 μm (13%), respectively, compared to the control (P = 0.023; n = 36). The B + T + U combination increased the proportion of the LM and SM by 7.0 ± 0.8%, but reduced the S + C fraction by 5.2 ± 0.23%. SOC was 30%, 25% and 23% in S + C, M and LM/SM fractions, and increased by 9.6 ± 1.0, 5.7 ± 0.8, 6.3 ± 1.1 and 4.2 ± 0.9 g kg−1 for LM, SM, M and S + C, respectively. MWD was not related to either soil respiration or soil moisture but decreased with higher SOC (R2 = 0.37, P = 0.014, n = 26) and increased with greater biomass production (R2 = 0.11, P = 0.045, n = 33). Our data suggest that within the timeframe of the study, biochar is stored predominantly as free particulate OC in the silt and clay fraction and promoted a movement of native SOC from larger-size aggregates to the smaller-sized fraction in the short-term (2 years).

Continuous plastic-film mulching increases soil aggregation but decreases soil pH in semiarid areas of China

Abstract: Plastic-film mulch is a globally applied agricultural practice. However, its effects on soil aggregation and pH have been hardly studied. We assessed the effects of plastic-film mulch on soil aggregate water-stability and pH in fields used for maize ( Zea mays L.) production, at two sites in a cold semiarid environment, China. Four treatments were used: (i) no plastic-film mulch and no straw incorporation, (ii) plastic-film mulch only, (iii) straw incorporation only, and (iv) straw incorporation plus mulch. Seven years after continuous treatment application, the use of plastic-film mulch increased the proportion of water-stable macroaggregates (>0.25 mm) in the top 15-cm soil layer by 16–28%, across sampling times and sites. Straw incorporation similarly increased the proportion of water-stable macroaggregates. However, the effects of mulch, on increasing the mean weight diameter of aggregates were greater in non-straw-incorporated soils than in straw-incorporated soils, and vice versa. Soil bulk density in the top 15-cm soil layer marginally increased in the mulched treatments, relative to the non-mulched treatments, while it decreased in straw-incorporated treatments. In addition, there was a decrease in soil pH, by 0.19–0.54 units, in the mulched, relative to the non-mulched soils. Combining our previous results, we suggested that increases in maize root growth and microbial activity were linked to the increased soil aggregation while accumulation in soil nitrate resulting from the stimulated soil nitrogen mineralization was responsible for the marginally decreased soil pH in the plastic-film mulched relative to the non-mulched soils, due to increased soil hydrothermal conditions.

Evaluation of methods for determining soil aggregate stability

Abstract: Aggregate stability is widely used as an indicator of soil health and erosion risk, however its use appears to be greatly hindered by a lack of standardised procedures and instrumentation. Aggregate stability can be measured using a number of different approaches each applying different types and levels of disruptive energy, which may or may not adequately match the type and level of disruptive energy experienced by soil aggregates in the field. This paper explores the effects of various approaches for the measurement of aggregate stability, and reports on the mechanisms responsible for the breakdown of intensively cultivated sandy clay loam and sandy loam in Tasmania, Australia. Stability was measured by exposing soil aggregates to rainfall simulation (RS), wet sieving (WS), ultrasonic vibration (UV) and clay dispersion (CD). Analysis was conducted on 2.00–4.75 mm aggregates that were either (i) air-dry (DRY) or (ii) re-moistened to field capacity at −10 kPa (MOIST). The mechanisms responsible for aggregate breakdown were explored by comparing values of aggregate stability determined using different fluids. Correlations between the various methods for determining aggregate stability were lower than expected. The highest correlation existed between the DRY—RS and DRY—WS (R2 = 0.749, P

Visual soil evaluation: A summary of some applications and potential developments for agriculture

Abstract: Visual soil evaluation techniques have gained popularity and are increasingly used in agriculture and soil science for research, consultancy and teaching purposes. We describe recent applications, developments, opportunities and limitations, mainly of the Visual Evaluation of Soil Structure (for topsoil (VESS) and for subsoil (SubVESS)), and of the Visual Soil Assessment (VSA). Data are taken from experiments on compaction and from assessments made in farmer’s fields in the UK, Brazil and New Zealand. The methods are widely used to detect compaction and are well-suited for monitoring changes in compaction status, particularly in relation to weather extremes. VESS proved useful in distinguishing grazing vs wheel compaction in the UK and Brazil by permitting detection of layers at different depths within the topsoil zone. The depths of compact layers are important for scoring management decisions for soil improvement. However the use of scores as limiting thresholds in different soil types needs the support of further soil measurements and/or additional visual assessments of soil and crop. VSA and VESS were also used to estimate the risk of significant soil emissions of nitrous oxide where compaction damage was present and rates of mineral N fertiliser were high. Visual assessments also have the potential to assess the risk of surface water runoff and nutrient loss. The potential role of soil colour was shown for the further development of visual evaluation techniques for a soil carbon storage index. Visual soil evaluation techniques also provide a useful visual aid for improving soil awareness in groups of stakeholders, helping the exchange of knowledge and ideas for innovation in agriculture.

Effects of straw application on coastal saline topsoil salinity and wheat yield trend

Abstract: Owing to an irrigation water shortage and a shallow underground water table in coastal zones, soil salinization is becoming a serious and complicated problem. Different practices are being explored to reduce its negative effect on land productivity. In this work, the effect of combined straw and inorganic N applications at different rates on topsoil (0–20 cm) salinity and wheat growth was evaluated in a coastal field. Maize straw was applied at the rates of 5.0 × 10 3 kg ha −1 (S) and 1.0 × 10 4 kg ha −1 (2S) and inorganic N was applied at the rates of 75 kg ha −1 (N1/2), 150 kg ha −1 (N), and 300 kg ha −1 (N2). Treatment without addition of straw but with inorganic N application at the rate of 150 kg ha −1 was used as the control (CK). Thus, there were six treatments: SN1/2, SN, SN2, 2SN, 2SN2, and CK. During the early growth stages (seedling, jointing, and booting) of wheat, straw application significantly decreased topsoil salinity from 13.8% to 30.4% in comparison to the CK treatment ( p 0.05), and the decrease was enhanced with increase in the straw application rate. This positive influence decreased substantially during wheat growth. Soil dissolved organic carbon and microbial biomass carbon both increased significantly ( p 0.05) after straw addition; in contrast, there was a significant reduction in available N from March to April. The greatest wheat grain yield and aboveground biomass were produced in 2SN2, and yield increased by 15.1% in comparison to CK. In contrast, yield decreased by 5.1–9.6% in SN, 2SN, and SN1/2. Thus, straw application may be an effective practice for reducing topsoil salinity in the coastal zones, and an adequate N supply should be applied to maximize crop yield.

Pyrolysis methods impact biosolids-derived biochar composition, maize growth and nutrition

Abstract: Land-applied biosolids (sludge) can improve food production sustainability through nutrient recycling. Biosolids-derived biochar may enhance soil fertility and overall soil health. However, there is little information on the conversion of biosolids to biochar using traditional kilns, or effects on biochar characteristics and plant growth. Biochar was produced from biosolids using two pyrolysis methods: 1) a traditional retort kiln (Top-lid Updraft-TLUD) intended for use by small farmers and gardeners, and 2) a laboratory muffle furnace, with the aim of evaluating biochar characteristics and its effects on Zea mays L. (corn) seed germination, growth and nutrition. Biochar produced in a muffle furnace contained 70% more ash, 78% more fixed carbon, and 63% less volatile matter than biochar produced by TLUD, which raised concern regarding TLUD-derived biochar toxicity The TLUD-derived biochar inhibited corn seed germination in a petri dish bioassay at biochar application rates from 2.5 to 100 Mg ha −1 . However, germination increased from 29% (control) to approximately 60%, at 60 Mg ha −1 or greater rates, with muffle furnace biochar. A greenhouse experiment was conducted to evaluate the growth and nutrition of corn grown in soil treated with 0, 5, 10, 20 and 60 Mg ha −1 biochar pre-incubated for two weeks in moistened soil. The muffle furnace biochar had no negative effect on plant growth and N nutrition, whereas the TLUD biochar at a 60 Mg ha −1 rate, reduced plant growth and increased plant N concentrations four-fold, compared to the control. Both biochars increased plant P concentrations with increasing application rates. Biosolids biochar produced via TLUD at rates below 20 Mg ha −1 may benefit crop production, although an incubation or weathering period may be necessary to limit potential short-term, phytotoxic effects. Future research needs include optimizing TLUD operational parameters and identifying weathering processes that improve biochar product quality for agronomic use.