Field Crops Research

In saline-alkaline soil, soil structural stability and phosphorus (P) availability are the limiting factors for crop yield. Organic amendments are proved to play a key role in soil quality, P availability and plant growth. A field experiment was carried out with different organic amendments level in the Yellow River Delta, five treatments were designed: (i) Control (no fertilization), (ii) NK (255 kg N ha−1 year−1 and 229 kg K ha−1 year−1), (iii) NPK (128 kg P2O5 ha−1 year−1 plus NK), (iv) NPKC1 (450 kg C ha−1 year−1 plus NPK) and (v) NPKC2 (900 kg C ha−1 year−1 plus NPK). The main results showed that: compared with NPK treatment, the mean weight diameter (MWD) of soil aggregates was increased by 33.8 % and 47.1 % in NPKC1 and NPKC2 treatments, respectively. And the percentage of water-stable aggregate (WSA) was also improved by 30.5 % and 40.16 % in NPKC1 and NPKC2 treatments, respectively. This was due to the increase of soil exchangeable Ca, soil organic carbon (SOC) and particulate organic carbon (POC) content, and the decrease in soil bulk density and exchangeable Na content, as well. Meanwhile, soil available P (AP), total P (TP), dicalcium P (Ca2-P) and octacalcium P (Ca8-P) contents were significantly increased with organic amendments addition. Based on the increase of soil structural stability and P availability, especially the accumulation of inorganic P (Pi) in soil macro-aggregates, root surface area and plant P use efficiency (PUE) were improved, which resulted in the grain yield increased by 12.2 % and 16.6 % in NPKC1 and NPKC2 treatments, respectively. Consequently, combined organic amendments and mineral fertilizer application were better in improving the soil structural stability, P availability and plant growth in saline-alkaline area.

Combined organic amendments and mineral fertilizer application increase rice yield by improving soil structure, P availability and root growth in saline-alkaline soil

Responses of soil labile organic carbon fractions and stocks to different vegetation restoration strategies in degraded karst ecosystems of southwest China

Knowledge of the soil organic carbon components and enzyme activities during long-term natural vegetation restoration is essential for managing the restoration of vegetation. In this study, the variations of soil organic carbon components (i.e., soil organic carbon (SOC), microbial biomass carbon (MBC), easily oxidized carbon (EOC), particulate organic carbon (POC)) and enzyme activities (i.e., amylase, catalase, urease, and sucrase) were measured in four vegetation types: control (grasslands, GL), forest (Xanthoceras sorbifolia, XS), and shrublands (Hippophae rhamnoides, HR; Caragana korshinskii, CK). We found that vegetation types significantly affect soil organic carbon components and enzyme activities. The SOC content of the XS plot is higher than HR, CK, and GL by 88.43%, 117.09%, and 37.53% at the 0-20 cm layer; the soil SOC content of the XS plot is higher than HR and CK by 27.04% and 26.87%, and lower than GL 12.90% at the 20-40 cm layer. The highest POC and urease were observed in the XS plot at a depth of 0-20 cm, that is, 1.32 g/kg and 98.51 mg/kg, respectively. The highest EOC, amylase, and sucrase were observed in GL at a depth of 0-20 cm, that is, 5.44 g/kg, 39.23, and 607.62 mg/g. On the vertical section of the soil, the SOC fractions and the enzyme activities were greater in the upper layer than in the lower layer for each vegetation type except for MBC and catalase activity. Correlation analysis demonstrated that the SOC and POC content significantly influenced urease and sucrase activities and that MBC significantly influenced catalase activity. These results provide important information about SOC fractions and enzyme activities resulting from vegetation types in the Loess Plateau and also supplement our understanding of soil C sequestration in vegetation restoration.

Changes in soil carbon fractions and enzyme activities under different vegetation types of the northern Loess Plateau

Applicability of biochar for limiting interrill erosion and organic carbon export of sloping cropland in a semi-arid area of China.

The aims of this research were to (i) systematically investigate the soil organic carbon (SOC) and labile SOC fraction dynamics over a period of 3 years under biochar amendment, (ii) reveal the relations of labile SOC fractions to SOC, and (iii) evaluate the sensitivity of SOC to biochar added at different rates by determining C pool management index (CPMI). The SOC, labile SOC fractions, and the CPMI in the 0–20-cm layer were analyzed via a 3-year field experiment of maize. Four biochar treatments were studied, with application rates of 0, 15.75, 31.5, and 47.25 t ha−1 (CK, BC1, BC2, and BC3, respectively). Biochar was applied manually before sowing only in the first year of this experiment; an equal mineral NPK fertilizer was applied to each treatment annually. The average data of this 3-year field study demonstrated that biochar incorporation significantly increased SOC, particulate organic carbon (POC), easily oxidizable carbon (EOC), light fraction organic carbon (LFOC), and microbial biomass carbon (MBC) by 31.75–83.62, 92.72–323.30, 29.90–51.55, 194.30–437.37, and 31.13–93.12%, respectively, compared to the control; their concentrations increased with increasing biochar addition rates, except for MBC. In addition, EOC, POC, and LFOC were significantly positively related with SOC. Compared to the control, the DOC contents were reduced after biochar addition, but the specific reasons for this finding need to be further studied. Biochar incorporation could not only significantly improve the soil quality via increasing the soil organic C fractions, but also increase C sequestration rates in the long term by increasing the non-labile C pool (NLC). The CPMI could be used as a representative index in evaluating the impacts of biochar on SOC content and soil quality.

Labile organic carbon fractions and carbon pool management index in a 3-year field study with biochar amendment

To compare the effects of maize stover and its biochar on soil P fractions and investigate the effects of different stover incorporation practices (direct return or pyrolysis) on the transformation of soil P fractions after a long-term field experiment. Total P, Olsen-P, inorganic P fractions, and organic P fractions were analyzed via a 5-year field experiment growing maize. The treatments were as follows: CK0 (no fertilizer application or amendment), CK (application of mineral NPK fertilizer), ST (application of maize stover at 7.5 t ha−1 along with mineral NPK fertilizer), and BC (application of biochar at 2.63 t ha−1, a rate approximately equivalent to a maize stover biomass of 7.5 t ha−1; the biochar was charred according to a 35% output ratio in the factory). All treatments received N mineral fertilizer at 120 kg N ha−1, P mineral fertilizer at 26 kg P ha−1, and K mineral fertilizer at 50 kg K ha−1 annually. Relative to the initial fractions in 2013, biochar generally increased the inorganic P fractions (Ca8-P, Ca10-P, Al-P, and Fe-P), and maize stover generally increased the organic P fractions (MLOP, MROP, and HROP), while both maize stover and its biochar significantly decreased O-P in the soil. After 5 years (in 2017), relative to CK treatment, amendment with maize stover and its biochar increased total P and decreased Olsen-P. The total inorganic P, Ca8-P, and Fe-P were significantly increased by biochar. Ca2-P and O-P were significantly decreased by maize stover and its biochar. Total organic P was increased with maize stover and biochar amendment. LOP and HROP were significantly increased under biochar application, and all organic P fractions were significantly increased under maize stover amendment. The application of maize stover and its biochar affected both organic and inorganic phosphorus fractions; biochar had a more advantageous effect on the soil inorganic P fractions, while stover had a greater effect on the content of organic P fractions.

Responses of organic and inorganic phosphorus fractions in brown earth to successive maize stover and biochar application: a 5-year field experiment in Northeast China

Maize straw and its biochar affect phosphorus distribution in soil aggregates and are beneficial for improving phosphorus availability along the soil profile

Successive applications of fertilizers blended with biochar in the soil improve the availability of phosphorus and productivity of maize (Zea mays L.)

The invention discloses a straw biochar-based soil phosphorus active conditioner and a preparation method thereof, and belongs to the technical field of agriculture. The straw biochar-based soil phosphorus active conditioner comprises, in parts by weight, acid-modified straw biochar 40-60 parts, an chelating agent 10-15 parts, a phosphorus-releasing bacteria agent 5-10 parts, an acidifying agent 10-15 parts and a filler 5-10 parts. The conditioner controls the adsorption-desorption performance of straw biochar on phosphorus at an appropriate level to meet the demand of crops for phosphorus, balances the fixation and activation of soil phosphorus, and prevents the risk of phosphorus leaching and releasing while meeting the needs of crops, and has good economic, environmental and ecologicalbenefits.

Di Wang

Papers

Labile organic carbon fractions and carbon pool management index in a 3-year field study with biochar amendment

Responses of organic and inorganic phosphorus fractions in brown earth to successive maize stover and biochar application: a 5-year field experiment in Northeast China

Maize straw and its biochar affect phosphorus distribution in soil aggregates and are beneficial for improving phosphorus availability along the soil profile

Successive applications of fertilizers blended with biochar in the soil improve the availability of phosphorus and productivity of maize (Zea mays L.)

Straw biochar-based soil phosphorus active conditioner and preparation method thereof