Temporal changes in rhizosphere biological soil quality indicators of wheat in response to nitrogen and straw incorporation

Replacing nitrogen in mineral fertilizers with nitrogen in maize straw increases soil water-holding capacity

Soil water-holding capacity decreases due to long-term mineral fertilizer application. The objective of this study was to determine how replacing mineral fertilizer with maize straw affected the soil water retention curve, soil water content, soil water availability, and soil equivalent pore size. Replacement treatments in which 25% (S25), 50% (S50), 75% (S75), and 100% (S100) of 225 kg ha-1 nitrogen from mineral fertilizer (CK) was replaced with equivalent nitrogen from maize straw were conducted for five years in the Loess Plateau of China. The Gardner model was used to fit the soil water retention curve and calculate the soil water constant and equivalent pore size distribution. The results indicated that the Gardner model fitted well. Replacing nitrogen from mineral fertilizer with nitrogen from straw increased soil specific water capacity, soil readily available water, soil delayed available water, soil available water, soil capillary porosity, and soil available water porosity over time. S25 increased field capacity and wilting point from the fourth fertilization year. S50 enhanced soil readily available water, soil delayed available water, soil available water, and soil available water porosity from the fifth fertilization year, whereas S25 and S75 increased these from the third fertilization year or earlier. Soil specific water capacity, soil readily available water, soil delayed available water, soil available water, soil capillary porosity, and soil available water porosity could better reflect soil water-holding capacity and soil water supply capacity compared with field capacity and wilting point.

Screening, cloning, immobilization and application prospects of a novel β-glucosidase from the soil metagenome

The soil environment for straw return is a rich and valuable library containing many microorganisms and proteins. In this study, we aimed to screen a high-quality β-glucosidase (BGL) from the soil metagenomic library and to overcome the limitation of the low extraction rate of resveratrol in Polygonum cuspidatum. This includes the construction of a soil metagenomic library, screening of BGL, bioinformatics analysis, cloning, expression, immobilization, enzymatic property analysis, and application for the transformation of polydatin. The results showed that the soil metagenomic library of straw return was successfully constructed, and a novel BGL was screened. The identified 1356 bp long BGL belonged to the glycoside hydrolase 1 (GH1) family and was named Bgl1356. After successful cloning and expression of Bgl1356, it was immobilized using chitosan. The optimum temperature of immobilized Bgl1356 was 50 °C, and the pH was 5. It exhibited good tolerance for various metal ions (CO2+, Ni2+, Cu2+, Mn2+, Na2+, Ca2+, and Ag+) and organic solvents (DMSO, Triton-X-10, and ethanol). Enzymatic kinetics assays showed that Bgl1356 had good affinity for the substrate, and the specific enzyme activity was 234.03 U/mg. The conversion rate of polydatin by immobilized Bgl1356 was 95.70 ± 1.08%, facilitating the production of high amounts of resveratrol. Thus, this paper reports a novel temperature-, organic solvent-, and metal ion-tolerant BGL that has good application prospects in the pharmaceutical industry.

Influence of tillage and residue management practices on productivity, sustainability, and soil biological properties of rice-barley cropping systems in indo-gangetic plain of India

Introduction

Conservation agriculture is a sustainable system of farming that safeguard and conserves natural resources besides enhancing crop production. The biological properties of soil are the most sensitive indicator to assess the short term impact of management practices such as tillage and residue incorporation.

Methods

Nine treatments of tillage and residue management practices [Reduced till direct seeded rice-zero till barley (RTDSR–ZTB); RTDSR–ZTB–green gram residue (Gg); Zero till direct seeded rice–zero till barley–zero till green gram (ZTDSR–ZTB–ZTGg); RTDSR–ZTB + rice residue at 4 t ha 1 (RTDSR–ZTBRR4); RTDSR–ZTBRR6; un-puddled transplanted rice (UPTR)–ZTB–Gg; UPTR–ZTBRR4; UPTR–ZTBRR6, and puddled transplanted rice (PTR)–RTB] executed under fixed plot for five years on crop productivity and soil biological properties under rice-barley production system.

Results

The shifting in either RTDSR or ZTDSR resulted in yield penalty in rice compared to PTR. The PTR recorded highest pooled grain yield of 3.61 ha−1. The rice grain yield reduced about 10.6% under DSR as compared to PTR. The ZTB along with residue treatments exhibited significantly higher grain yield over ZTB, and the RTDSR-ZTBRR6 registered highest pooled grain yield of barley. The system productivity (12.45 t ha−1) and sustainable yield index (0.87) were highest under UPTR-ZTBRR6. Biological parameters including microbial biomass carbon, soil respiration, microbial enzymes (Alkaline phosphatase, nitrate reductase and peroxidase), fluorescein diacetate hydrolysis, ergosterol, glomalin related soil proteins, microbial population (bacteria, fungi and actinobacteria) were found to be significantly (p < 0.05) effected by different nutrient management practices. Based on the PCA analysis, Fluorescein diacetate hydrolysis, microbial biomass carbon, soil respiration, nitrate reductase and fungi population were the important soil biological parameters indicating soil quality and productivity in present experiment. The results concluded that UPTR-ZTBRR6 was a more suitable practice for maintaining system productivity and soil biological health.

Discussion

The understanding of the impact of different tillage and residue management practices on productivity, soil biological properties and soil quality index under rice-barley cropping system will help in determining the combination of best conservation agriculture practices for improved soil quality and sustainable production.

Thermochemical digestate fertilizer from solid waste: Characterization, labile carbon dynamics, dehydrogenase activity, water holding capacity and biomass allocation in banana

Thermochemical digestion is a rapid technology of biowaste management resulting in the instant production of organic fertilizer. Characterization and assessment of its suitability as an organic fertilizer is essential for recommendation for crop application. Biowaste and the thermochemical digestate were subjected to physicochemical and biochemical characterization and the compost maturity parameters assessed. The product integrated with inorganic fertilizers was tested in an Ultisol grown with banana in comparison with farmyard manure based fertilizers. Temporal variation in soil reaction, water holding capacity, carbon dynamics, dehydrogenase activity and plant biomass were determined. The thermochemical digestate fertilizer had a bulk density (0.76 Mg m^-3), pH (neutral), C:N ratio (16.26), CEC (85.70 cmol₍₊₎ kg^-1), CEC/ TOC ratio (3.99), Fertilizing index (4.7) and a Clean index (5.0). Field evaluation revealed enhanced water holding capacity (38.75-83.17%). Total carbon increased with consistently high labile (R² = 0.9551) and non labile carbon fractions and the lowest average lability index (0.78). Dehydrogenase activity at harvest enhanced by 72.81%. An even biomass allocation resulted in 38.84% more biomass production in the fruit over farmyard manure based treatments. In addition to ensuring the safety of the environmental ecosystem, the thermochemical digestate conformed to be a quality resource favoring microbial proliferation and carbon sequestration, thereby restraining carbon dioxide emission. The thermochemical digestate fertilizer based nutrition serves the key deliverables of natural resource management, ecofriendly rapid disposal of biowaste and quality organic fertilizer for banana in Ultisols.