Showing papers in "Communications in Soil Science and Plant Analysis in 2010"

Use of Single Extraction Methods to Predict Bioavailability of Heavy Metals in Polluted Soils to Rice

Abstract: Human exposure to toxic heavy metals via dietary intake is of increasing concern. Heavy-metal pollution of a rice production system can pose a threat to human health. Thus, it was necessary to develop a suitable extraction procedure that would represent the content of metal available to rice plants (Oryza sativa L.). The aim of this study was to predict, on the basis of single extraction procedures of soil heavy metals, the accumulation of heavy metals (cadium, lead, copper, and zinc) in rice plants. Six extracting agents [Mehlich 1, Mehlich 3, EDTA (ethylenediaminetetraacetic acid), DTPA–TEA (diethylenetriaminepentaacetic acid–triethanolamine), ammonium acetate (NH4OAc), and calcium chloride (CaCl2)] were tested to evaluate the bioavailability of heavy metals from paddy soils contaminated with lead–zinc mine tailings to rice. The extraction capacity of the metals was found to be of the order EDTA > Mehlich 3 > Mehlich 1 > DTPA–TEA > NH4OAc > CaCl2. The correlation analysis between metals extracted with d...

Simple and Rapid Laboratory Method for Rewetting Dry Soil for Incubations

Abstract: Soil microbial activity is greatly affected by soil water content. Determining the appropriate moisture content to rewet soils that have been dried in preparation for laboratory incubations to determine microbial activity can be laborious and time-consuming. The most common methods used achieve sufficient moisture content for peak microbial respiration are gravimetric water content, soil matric potential, or percentage of water-filled pore space (WFPS). Alternatively, a fast, simple, and accurate way to ensure that a given soil receives the appropriate amount of water for peak soil microbial respiration is to rely on natural capillary action for rewetting the dry soil. The capillary method is related to the gravimetric method for water uptake and has a strong correlation with WFPS. A microbial respiration test was conducted to compare rewetting methods. The 24-h carbon dioxide (CO2) / carbon (C) results were very similar and strongly correlated using the gravimetric method and the capillary method for rew...

Simple, Robust Method for Quantifying Silicon in Plant Tissue

Abstract: Low silicon (Si) content in rice, sugarcane and other Si-accumulating crops can adversely affect crop performance because it creates reduced tolerance to both abiotic and biotic stresses. Assessing the Si status of a crop typically depends upon accurately measuring Si accumulation in plant tissue. Methods involving wet digestion of plant tissue followed by colorimetric determination of Si have proven attractive because they are both rapid and do not require costly, specialized instrumentation. Some popular wet-digestion methods are reported to provide highly variable and inconsistent results. A systematic study to identify and address the sources of variability associated with wet digestion for Si analysis found that modifications that reduce excessive foaming during wet digestion of plant tissue in strong alkali and peroxide significantly reduce variability. Unstable and variable color development associated with the molybdenum blue reaction is a concern in the colorimetric determination of Si in digests...

Influence of Urea and Ammonium Sulfate on Soil Acidity Indices in Lowland Rice Production

Abstract: Urea and ammonium sulfate are principal nitrogen (N) sources for crop production. Two field experiments were conducted during three consecutive years to evaluate influence of urea and ammonium sulfate application on grain yield, soil pH, calcium (Ca) saturation, magnesium (Mg) saturation, base saturation, aluminum (Al) saturation, and acidity (H + Al) saturation in lowland rice production. Grain yield was significantly influenced by urea as well as ammonium sulfate fertilization. Soil pH linearly decreased with the application of N by ammonium sulfate and urea fertilizers. However, the magnitude of the pH decrease was greater by ammonium sulfate than by urea. The Ca and Mg saturations were decreased at the greater N rates compared to low rates of N by both the fertilizer sources. The Al and acidity saturation increased with increasing N rates by both the fertilizer sources. However, these acidity indices were increased more with the application of ammonium sulfate compared with urea. Rice grain yield had negative associations with pH, Ca saturation, Mg saturation, and base saturation and positive associations with Al and acidity saturation. This indicates that rice plant is tolerant to soil acidity.

Comparisons of Yield, Water Use Efficiency, and Soil Microbial Biomass as Affected by the System of Rice Intensification

Abstract: To compare the effects of the system of rice intensification (SRI) on yield, water use efficiency, and microbial biomass in associated rice soils, a field experiment was conducted in 2004 at the Agriculture Experimental Farm of Zhejiang University in Zhejiang Province, China. The treatments evaluated were traditional flooding (TF) vs. SRI cultivation methods. Grain yield in the SRI treatment was 26.4% greater than that in the TF treatment, reducing water use by 461.5 mm. Compared to TF, SRI increased water use efficiency by 91.3% and irrigation water use efficiency by 194.9%. Soil microbial indicators during the rice‐growing season also diverged between TF and SRI. Microbial biomass C (MBC) was in the range of 101–196 mg kg−1 for TF vs. 113–224 mg kg−1 for SRI; microbial biomass N (MBN) was in the range of 14–33 mg kg−1 for TF vs. 28–53 mg kg−1 in SRI. Compared to TF, SRI significantly increased both MBC and MBN, regardless of sampling date.

Determination of Major and Trace Elements in Plant Samples by Inductively Coupled Plasma–Mass Spectrometry

Abstract: The determination of several trace elements [arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), molybdenum (Mo), nickel (Ni), and lead (Pb)] in plant samples using inductively coupled plasma–mass spectrometry (ICP‐MS) was evaluated. It was established experimentally that moderate amounts (0.2–2%) of dissolved solids decreased the analyte signals significantly. Internal standardization with Rh was efficiently used to compensate for these matrix effects. The accuracy of the method was verified using reference materials digested according to two different procedures: dry ashing and microwave digestion. No significant differences were observed between measured concentrations and certified values. The investigation was next extended for the determination of major elements [aluminum (Al), boron (B), calcium (Ca), iron (Fe), potassium (K), magnesium (Mg), manganese (Mn), sodium (Na), phosphorus (P), and zinc (Zn)] on the same reference materials. The ICP‐MS values agree well with the values sup...

Effects of Controlled Release Urea on the Yield and Nitrogen Nutrition of Flooded Rice

Abstract: Nitrogen (N) loss is one of the key problems faced by rice farmers, and Nitrogen-use efficiency in rice is often poor as a result of high N loss through volatilization, leaching, and denitrification. One of the ways to improve N efficiency is by using controlled-release urea (CRU). The CRU generally outperformed granular urea fertilizer in reducing N losses, stimulating plant growth, and increasing N concentrations. A field experiment with the flooded rice variety MR220 was conducted to compare the effect of six different types of CRU fertilizers on yield and N nutrition of a flooded rice cultivar. Bakau series soil (Typic Tropaquept) was used in this study. Rice plants were grown in a cylindrical culvert measuring 90 cm in diameter by 60 cm in height, and all culverts were filled with soil (approx. 210 kg). The soil was flooded and preincubated for 3 weeks to stabilize physiochemical properties before sowing. The experiment was carried out over two planting seasons on the same plot using a completely ran...

Diagnosis of Secondary and Micronutrient Deficiencies and Their Management in Rainfed Agroecosystems: Case Study from Indian Semi‐arid Tropics

Abstract: Rainfed agriculture in the semi‐arid tropical (SAT) regions of India is greatly influenced by water shortages caused by low, highly variable, and erratic rainfall. However, apart from water shortages, crop productivity in these regions is also affected by low fertility. Little effort has been devoted to diagnosing and managing the nutrient‐related problems in farmers' fields in the SAT regions of India. The ongoing integrated watershed management program by the International Crops Research Institute for the Semi‐arid Tropics and its partners provided the opportunity to diagnose the soil infertility‐related problems by soil testing, develop nutrient management protocols, and determine on‐farm crop responses to fertilization in the SAT zone of India. This article discusses examples from recent research on the diagnosis of multinutrient deficiencies and on‐farm crop responses to fertilization. Results of analyses of soil samples from farmers' fields in several districts of Andhra Pradesh, Karnataka, Tamil Na...

Tillage Depth Effects on Soil Physical Properties, Sugarbeet Yield, and Sugarbeet Quality

Abstract: Tillage depth influences the soil–water–plant ecosystem, thereby affecting crop yield and quality. The effects of tillage depth on soil physical properties and sugarbeet (Beta vulgaris L.) yield and quality were evaluated. A field study composed of two tillage depths [10 cm, referred to as shallow (ST), and 20 cm, referred to as deep (DT)] was conducted on a Lihen sandy loam soil in spring 2007 at the Agricultural Research Service (ARS) irrigated research farm near Williston, North Dakota. Soil bulk density (ρb), gravimetric water content (θw), and saturated hydraulic conductivity (Ks) were measured three times during the growing season at four depth increments to 40 cm deep. Samples were taken approximately 0.5 m apart within the crop row of irrigated sugarbeet. Soil air-filled pore volume (ea) was calculated from soil bulk density and water content data. Soil penetration resistance (PR) was also measured in 2.5-cm increments to a depth of 35 cm. Roots were hand-harvested from each plot, and each sample ...

Effect of Foliar-Applied Humic Acid to Dry Weight and Mineral Nutrient Uptake of Maize under Calcareous Soil Conditions

Abstract: Greenhouse research was conducted to determine the effects of foliar application of humic acid on dry matter and some nutrient element uptake of maize grown under calcareous soil conditions. Agricultural lime was used to obtain five calcium carbonate (CaCO3) doses (0, 5, 10 20, and 40%) and three foliar application doses of humic acid (0, 0.1, and 0.2%) sprayed at 20 and 35 days after emergence. Although the dry weight and mineral element uptake of maize were affected negatively, especially at 20 and 40% of lime levels, foliar application of humic acid had a statistically significant positive effect on dry weight and copper (Cu), zinc (Zn), and manganese (Mn) uptakes (P < 0.01) of maize plants. The greatest dry weight and Cu and sodium (Na) uptakes were obtained from the 0.01% humic acid treatment. The interaction of lime and humic acid was also statistically significant on dry weight, nitrogen (N), phosphorus (P), calcium (Ca), magnesium (Mg), Cu, Zn, and Mn uptake (P < 0.01).

Growth, Root Characteristics, and Leaf Nutrients Accumulation of Four Faba Bean (Vicia faba L.) Cultivars Differing in Their Broomrape Tolerance and the Soil Properties in Relation to Salinity

Abstract: The effects of salinity on four faba bean (Vicia faba L) cultivars [Giza 429, Giza 843, Misr 1 (Orobanche-tolerant), and Giza 3 (Orobanche-susceptible)] and soil properties were investigated in a pot experiment with addition of 0, 50, and 100 mM sodium chloride (NaCl) for 9 weeks. Salinity significantly decreased calcium (Ca2+), magnesium (Mg2+), potassium (K+), bicarbonate (HCO3 −), and sulfate (SO4 2−) while significantly increasing sodium (Na+), chloride (Cl−), pH, and electrical conductivity (EC; dS m−1). Root length density (cm cm−3), root mass density (mg cm−3), total dry weight, and salt-tolerance indexes were significantly reduced as a result of application of salinity. The results presented support evidence on the positive relationship between Orobance tolerance and salt tolerance in the three cultivars (Giza 429, Giza 843, and Misr 1). This adaptation was mainly due to a high degree of accumulation of inorganic nitrogen (N), phosphorus (P), K+, Ca2+, and Mg2+ and lesser quantities of Na+ and Cl−...

Modifications to the New Soil Extractant H3A-1: A Multinutrient Extractant

Abstract: A new soil extractant (H3A-1) with the ability to extract ammonium (NH4) nitrogen (N), nitrate (NO3) N, and phosphorus (P) from soil was originally developed and tested against 32 soils (Haney et al. 2006). H3A-1 is composed of organic acid root exudates, which are naturally occurring, and lithium citrate. In this study, H3A-1 was modified to reduce the extractable iron and aluminum and improve the nutrient extracting relationships with other well-known soil extractants. Correlations show improved relationships with NO3, NH4, PO4, P, potassium, calcium, and zinc when compared to the original H3A-1 as well as standard soil-test methods [Olsen, potassium chloride (KCl), water, Mehlich 3, Bray 1, ammonium acetate (NH4 OAc), and diethylenetriaminepentaacetic acid (DTPA)]. The modifications were tested against the results from the North American Proficiency Testing (NAPT) database, which included 60 soils, varying in pH, organic carbon, and clay content.

Potassium Leaching as Affected by Soil Texture and Residual Fertilization in Tropical Soils

Abstract: Potassium (K) leaching is affected by soil texture and available K, among other factors. In this experiment, effects of soil texture and K availability on K distribution were studied in the presence of roots, with no excess water. Soils from two 6-year field experiments on a sandy clay loam and a clay soil fertilized yearly with 0, 60, 120, and 180 kg ha−1 of K2O were accommodated in pots that received 90 kg ha−1 of K2O. Soybean was grown up to its full bloom (R2). Under field conditions, K leaching below the arable layer increased with K rates, but the effect was less noticeable in the clay soil. Potassium leaching in a sandy clay loam soil was related to soil K contents from prior fertilizations. With no excess water, in the presence of soybean roots, K distribution in the profile was significant in the lighter textured soil but was not apparent on the heavier textured soil.

Effect of Integrated Nutrient Management on Soil Physical Properties and Crop Productivity under a Maize (Zea mays)–Mustard (Brassica campestris) Cropping Sequence in Acidic Soils of Northeast India

Abstract: A five-year (2001/02–2006/07) field experiment was carried out on acidic clay loam soil classified as Typic Hapludalf with a maize–mustard crop sequence to study the effect of continuous application of nitrogen, phosphorus, and potassium (NPK) fertilizers alone and in combination with lime, farmyard manure (FYM), and biofertilizers on soil physical properties, soil organic carbon (SOC), soil microbial biomass carbon (SMBC), and crop yields on the hilly ecosystem of Meghalaya. Significant improvement in the soil physical conditions of the soil was observed under integrated application of organic manure and inorganic fertilizers. Addition of NPK fertilizers along with organic manure, lime, and biofertilizers increased soil organic carbon (SOC) content, aggregate stability, moisture-retention capacity, and infiltration rate of the soil while reducing bulk density. The SOC content under the treatment of 100% NPK + lime + biofertilizer + FYM was significantly greater (68.58%) than in control plots. Maize and m...

Diethylenetriaminepentaacetic Acid–Extractable Micronutrients Status in Soil under a Rice–Wheat System and Their Relationship with Soil Properties in Different Agroclimatic Zones of Indo‐Gangetic Plains of India

Abstract: Available micronutrient status of zinc, copper, manganese, and iron (Zn, Cu, Mn, and Fe) in surface soil samples under a rice–wheat system collected from farmers' fields in 40 districts representing different agroclimatic zones of the Indo‐Gangetic Plain (IGP) were determined. The selection of farmers, villages, blocks, and districts within an agroclimatic zone was made on the basis of a multistage statistical approach. In Trans‐Gangetic Plains, the diethylenetriaminepentaacetic acid (DTPA)–extractable Zn ranged from 0.11 to 5.08, Cu ranged from 0.22 to 4.72, Mn ranged from 2.9 to 101.2, and Fe ranged from 1.05 to 97.9 mg kg−1. In the Upper Gangetic Plains, the DTPA‐extractable Zn ranged from 0.04 to 2.53, Cu ranged from 0.06 to 4.32, Mn ranged from 11.1 to 421.0, and Fe ranged from 3.48 to 90.2 mg kg−1. In the Middle Gangetic Plains, the DTPA‐extractable Zn ranged from 0.17 to 8.60, Cu ranged from 0.09 to 7.80, Mn ranged from 3.0 to 155.1, and Fe ranged from 9.22 to 256.7 mg kg−1. In the Lower Gangetic P...

Effect of Chromium and Lead on Yield, Chemical Composition of Essential Oil, and Accumulation of Heavy Metals of Mint Species

Abstract: A pot culture experiment was conducted to investigate the effect of increasing levels (30.0 and 60.0 mg kg−1 soil) of chromium and lead on the yield, chemical composition of essential oil, and phytoaccumulation of heavy metals of three mint species (Mentha arvensis, M. piperita, and M. citrata). The fresh herbage yield of M. arvensis was not significantly affected by the application of chromium and lead, but its essential oil yield was significantly decreased by the application of chromium and lead as compared to the control. The fresh herbage, root yield, and essential oil yield of M. piperita were significantly increased and those of M. citrata were decreased by the increase in the levels of chromium and lead applications. The levels of α-pinene, β-pinene, sabinene, β-myrcene, limonene, menthone, and isomenthone in M. arvensis and M. piperita oil and of sabinene, pinene, and linalyl acetate in M. citrata oil were considerably affected by the application of chromium and lead to soils as compared to contr...

Protective Role of Selenium on Garlic Growth under Cadmium Stress

Abstract: The stimulative action and detoxifying effect of selenium on garlic growth under cadmium stress were investigated. Selenite treatment can promote mitosis of garlic root-tip cells and growth of roots and seedlings. Garlic has a strong ability to accumulate the selenium from soil, and selenium content was greatest in garlic seedlings. Addition of selenite at a concentration of 2.0 μg kg−1 in soil could decrease cadmium content in garlic and protect the seedling growth. The selenium has been shown to have an effective protective role on garlic growth under cadmium stress.

Effects of Different Agricultural Wastes on Some Soil Quality Indexes in Clay and Loamy Sand Fields

Abstract: Effects of manure (M), hazelnut husks (HH), tea waste (TEW), and tobacco wastes (TOW) on some soil quality indexes were monitored for more than 2 years in a clay field and a loamy sand field While soil organic carbon (OC) contents were around 2% after 30 months in clay, they were generally less than 2% after 7 months in loamy sand Organic wastes generally increased aggregate stability (AS) and field capacity and decreased bulk density (BD) of the soils Soil pH decreased with TEW and increased with M treatment Tobacco wastes exerted the greatest effect on AS, EC, and nitrate (NO3) nitrogen (N) Hazelnut husks and TEW had the greatest effect on soil respiration in clay and loamy sand soils, respectively While BD and pH increased, the other indicators generally decreased between the first and the last sampling Soil quality can be improved in coarse-textured soils using TEW and HH and in fine-textured soils using TEW and M

Significance of Enzyme Activities in Soil Nitrogen Mineralization

Abstract: This study was undertaken to assess the relationship between nitrogen (N) mineralization in soils treated with eight lime application rates, with four field replications, and the activities of six amidohydrolases involved in N cycling and four glycosidases involved in carbon (C) cycling in soils. Nitrogen mineralization was studied at 20 or 30 °C for 20 weeks, and with the exception of N‐aceyl‐β‐D‐glucosaminidase (NAGase; EC 3.2.1.30) activity, which was assayed at both temperatures, the enzyme activities were assayed at 30 °C at their optimal pH values. Results showed that among the eight enzyme activities studied, NAGase activity was the most significantly correlated with the cumulative amounts of N mineralized in 32 soil samples at 20 °C (r = 0.87***) and at 30 °C (r = 0.95***). The cumulative amounts of N mineralized at 30 °C were also significantly correlated with arylamidase and L‐aspartase activities, with r values of 0.61*** and 0.52**, respectively. Because NAGase activity is involved in both...

Effects of Boron Fertilizer on Tomato, Pepper, and Cucumber Yields and Chemical Composition

Abstract: In many parts of the world, boron (B) levels are insufficient for potential production. Boron deficiency is also widespread in the Anatolia region of Turkey. Boron deficiency could impact production and quality of tomatoes (Lycopersicon esculentum L.), pepper (Capsicum annum L.), and cucumber (Cucumis sativus L.). A two-year greenhouse experiment was conducted to study yield and quality response of three vegetables to B addition (0, 1, 2, 3, and 4 kg B ha−1). The optimum economic B rates (OEBR) were 2.3, 2.6, 2.4 kg B ha−1, resulting in soil B concentrations of 0.33, 0.34 and 0.42 mg kg−1. Independent of plant species, B application decreased tissue nitrogen (N), calcium (Ca), and magnesium (Mg) but increased tissue phosphorus (P), potassium (K), iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu) concentrations. We conclude that a B addition of 2.5 kg ha−1 is sufficient to elevate soil B levels to nondeficient levels. Similar studies with different soils and initial soil-test B levels are needed to con...

Effect of Nitrogen on Yield and Some Quality Parameters of Sweet Corn

Abstract: Sweet corn consumption has increased considerably worldwide. Sweet corn is produced for human consumption as either a fresh or a processed product. The nutrient composition of sweet corn is very important for human health and diet. This study aimed to determine the best nitrogen (N) dosage for sweet corn. Kernel mineral composition and protein content were determined for different N rates. The research was carried out during 2003 and 2004 in Sanliurfa, Turkey. Nitrogen application rates were 120, 160, 200, 240, 280, 320, and 360 kg N ha−1 with control. The fresh ear yield per hectare and the protein and mineral contents of kernel were significant (P < 0.01). The lowest yield was obtained at low N applications, whereas increasing N applications increased the fresh ear yield and protein content of kernel. Nitrogen-use efficiency increased up to 320 kg ha−1 N dosage (60.2% and 58.6% for 2003 and 2004, respectively), and a decrease was seen at 360 kg ha−1 N dosage. Leaf area index and root dry matter increase...

Organic and Inorganic Amendments Affect Soil Concentration and Accumulation of Cadmium and Lead in Wheat in Calcareous Alkaline Soils

Abstract: Irrigation with untreated effluent in periurban agriculture could result in accumulation and bioconcentrations of cadmium (Cd) and lead (Pb). Different amendments were used to investigate their effect on availability, concentration, and uptake of metals by wheat in texturally different soils. Crop was irrigated with water containing Cd and Pb at 20 mg L−1, thereby adding 260 mg pot−1 of each metal. Amendments included calcium carbonate at 6 or 12%, gypsum at 50 or 100% of the soil gypsum requirement, farm manure at 7.50 or 15.00 g kg−1 soil, and a control. Amendments decreased ammonium bicarbonate diethylenetriaminepentaacetic acid (AB-DTPA)–extractable Cd and Pb concentrations and uptake by wheat. Dry matter, concentration, uptake, and extractability of Cd and Pb were greater in sandy loam soil compared with those in sandy clay loam soil irrespective of amendments. Sequential extraction showed that more metals were extracted from the control in all fractions and that predominantly metals were found in th...

Influence of Organic, Chemical, and Integrated Management Practices on Soil Organic Carbon and Soil Nutrient Status under Semi-arid Tropical Conditions in Central India

Abstract: Soil organic carbon (SOC), macro- and micronutrient status, and nitrogen (N) mineralization were studied in a soil profile managed with organic (OMP), chemical (CMP), and integrated (IMP) management practices for 3 years (2004–7) under a soybean–durum wheat cropping sequence. The most significant buildup of SOC and nutrients was in OMP, followed by IMP and then CMP. The OMP had 15.8 and 7.3% more SOC content than the CMP and IMP, respectively. The concentration of nitrate N was significantly greater in the OMP and IMP than in the CMP. The amount of ammonium N was less than nitrate N in OMP and IMP, indicating the high nitrification ability of the soil. A buildup of the micronutrient cation content was also noticed in the surface layer in the OMP and IMP plots. The OMP and IMP had a significantly greater mineralization rate of N than did CMP, and it was greatest in the top 0- to 15-cm soil layer.

Evaluation of Selected Extractants for Plant-Available Silicon in Rice Soils of Southern India

Abstract: The extractable silicon (Si) using selected extractants irrespective of the soils used for the study was in the order of 0.005 M sulfuric acid (H2SO4) > 0.1 M citric acid > N sodium acetate (NaOAc) 2 > N NaOAc 1 > 0.5 M acetic acid 3 > 0.5 M acetic acid 2 > 0.5 M acetic acid 1> 0.01 M calcium chloride (CaCl2) > 0.5 M ammonium acetate (NH4OAc) > distilled water 4 > distilled water 1. Silicon extraction with N NaOAc 1 appeared to be the most suitable for evaluating Si, followed by extraction with 0.5 M acetic acid 2 and N NaOAc 2. These extractants showed the greatest degree of significant correlation with the percentage of Si in straw and grain, as well as Si uptake by straw and grain. These methods also rapidly extract soil Si in comparison to the other methods and appear to be the most suitable for routine soil testing for plant-available Si in the rice soils of southern India.

Incomplete Acetylene Inhibition of Nitrous Oxide Reduction in Potential Denitrification Assay as Revealed by using 15N-Nitrate Tracer

Abstract: One lake sediment and three soils for rice production were used to test the effectiveness of inhibiting of nitrous oxide (N2O) reduction to dinitrogen gas (N2) by acetylene (C2H2) using 15N tracer. Regardless of the sources of the samples, results show that in presence of C2H2, significant isotopic enrichment of 15N of N2 was found at end of a typical denitrification assay. The δ15N of N2 value increased from 0‰ to 7.8–19.3‰ and 7.5–10.6‰ for the treatment with addition of 0.05 and 0.2 mg 15N nitrate, respectively. Such 15N enrichment can be interpreted as N2 formation accounting for 15.3% and 2.5% of the total added N in these two treatments, respectively. Nitrous oxide accumulation in presence of C2H2 could not account for the total added N. The result indicates incomplete inhibition of N2O reduction to N2 by C2H2 in denitrification when N2O reduction enzyme is developed.

Predicting Plant Phosphorus Requirements for Hawaii Soils using a Combination of Phosphorus Sorption Isotherms and Chemical Extraction Methods

Abstract: Phosphorus (P) is an essential nutrient for plant growth and reproduction. One of the tasks of soil testing is to identify whether the soil P level is sufficient to meet crop requirements, and if not, to provide an estimate of the quantity of P that must be added for good growth of a given crop. Data for 12 soils (11 series) from Hawaii were used to develop correlations between critical P concentrations in soil solution derived from P sorption isotherms with P extracted with Mehlich 3, Olsen, or modified Truog solutions. Extractable P, in turn, was correlated with P fertilizer requirements. Critical P levels in soil solution reported in the literature for various crops ranged from 0.005 mg L−1 for cassava (Manihot esculenta) to 0.30 for lettuce (Lactuca sativa) and to 1.6 for nonmycorrhizal onions (Allium cepa). The P buffer coefficient, defined as the ratio of fertilizer P added to extractable P, averaged 2.2, 4.2, and 8.6 for the modified Truog, Olsen, and Mehlich 3, respectively. Phosphorus requirement...

Yield, Potassium Uptake, and Use Efficiency in Upland Rice Genotypes

Abstract: Potassium (K) is an essential nutrient for higher plants. Information on K uptake and use efficiency of upland rice under Brazilian conditions is limited. A greenhouse experiment was conducted with the objective to evaluate influence of K on yield, K uptake, and use efficiency of six upland rice genotypes grown on Brazilian Oxisol. The K rate used was zero (natural soil level) and 200 mg K kg–1 of soil. Shoot dry weight and grain yield were significantly influenced by K level and genotype treatments. However, K × genotype interactions were not significant, indicating similar responses of genotypes at two K levels for shoot dry weight and grain yield. Genotypes produced grain yield in the order of BRS Primavera > BRA 01596 > BRSMG Curinga > BRS 032033 > BRS Bonanca > BRA 02582. Potassium concentration in shoot was about sixfold greater compared to grain, across two K levels and six genotypes. However, K utilization efficiency ratio (KUER) (mg shoot or grain yield / mg K uptake in shoot or root) was about 6...

Phosphorus Availability and Early Corn Growth Response in Soil Amended with Turkey Manure Ash

Abstract: Incinerating turkey manure is a new option in the USA to generate renewable energy and to eliminate environmental problems associated with manure stockpiling. Incineration produces turkey manure ash (TMA) with a nutrient content of 43 g phosphorus (P) kg−1 and 100 g potassium (K) kg−1. We conducted a greenhouse pot study using a low P (6 mg kg−1) and high K (121 mg kg−1) soil/sand mixture with a 7.0 pH to evaluate early growth response of corn (Zea mays L.) to TMA. A control and five rates based on P (5.6, 10.9, 16.5, 21.9, and 27.2 mg kg−1) and respective K contents in TMA were compared with triple-superphosphate and potassium chloride fertilizer. Plant height and stalk thickness at 24 and 31 days after emergence (DAE) were greatest with the fertilizer, but no differences were detected at the final sampling (52 DAE). Regardless of nutrient source, plant biomass increased with P rate. Because of faster initial plant development, corn dry matter 52 DAE was 15 to 20% greater with fertilizer than with TMA. C...

Organic-Matter Pools of Soil under Pines and Annual Cultures

Abstract: When submitted to different uses and managements, soils can suffer alterations in the amount and in the quality of carbon and nitrogen present in the soil. This study's objective was to evaluate carbon and nitrogen in different compartments of the organic matter of the soil under savannah, 30-year-old pine plantation, and annual cultivations with corn and soy under conventional preparation and direct planting after 10 years of age. The substitution of the savannah for the pines and annual cultures reduces the carbon and total nitrogen in the soil. Among the compartments, only the particulate-free light fraction is not reduced in the Pinus in relation to the savannah. No tillage presents potential for improvement of the quality of the soil to make the fractions of carbon more labile in the soil. The more labile fractions reflect the alterations well imposed in the use and management of the soil, and they can be used as sensitive and premature indicators of the quality of the soil. They can be used for calc...

Nitrogen Mineralization from Five Manures as Influenced by Chemical Composition and Soil Type

Abstract: The high cost of chemical fertilizers has forced farmers to switch to intensive use of locally available manures. Two laboratory incubation experiments were carried out in Sudan to study the effects of manure (chicken, farmyard, pigeon, and goat), chemical fertilizer, and four soil types (Ustert, Fluvent, Orthid, and Psamment) on nitrogen (N) mineralization. Net N mineralization in light soils (248, 529 mg N kg−1) was significantly (P ≤ 0.02) greater than in heavy soils (44, 212 mg N kg−1). Manure pH (R 2 = 0.9, P ≤ 0.01), lignin content (R 2 = 0.74, P ≤ 0.05), lignin / total nitrogen (TN; R 2 = 0.72, P ≤ 0.05), polyphenols/TN (R 2 = 0.75, P ≤ 0.05), and TN (R 2 = 0.76, P ≤ 0.05) were found to be the best parameters to determine N mineralization from manures. These findings support earlier studies that N release from organic N of different sources depends on soil type and chemical composition of the manure.