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• Minimum data set includes four factors, which reflect the integrated soil function. • Significant differences in soil quality between different productivity. • The significant positive correlation between SQI and wheat yield. • Available N, SOM and microbial biomass N to total N ratio were limiting factors. The double-cropping of winter wheat and summer maize is a major grain production system in China which occupies more than half the double-cropping systems of the country's dryland area. This cropping system has experienced a decreased crop yield and soil quality and the limiting factors are poorly known. The goal of this study was to conduct a systematic evaluation of wheat yield and soil quality from 132 fields along a regional scale in China. The specific objectives were (i) to establish a minimum data set (MDS) in wheat phase under the wheat-maize cropping system (ii) to evaluate soil quality of the wheat field and determine the factors limiting wheat productivity. The wheat-maize cropping system was partitioned into three productivity levels (high, medium and low) according to the wheat yield. Twenty-six soil indicators, including soil microbiological, chemical and physical factors were measured and analyzed. Using Pearson correlation analysis we identified eight key soil indicators that determine wheat yield. We then used principal component analysis to determine an MDS, which included soil organic matter, alkali-hydrolyzable nitrogen, the ratio of microbial biomass nitrogen to total nitrogen, and available zinc. One-way analysis of variance based on the individual contribution of each MDS indicators under three productivity, revealed available nitrogen, soil organic matter and the ratio of microbial biomass nitrogen to total nitrogen was the most important indicators on limiting wheat yield. A soil quality index (SQI) based on scoring and weighting of MDS indicators was integrated as a tool for assessing farmland soil quality. Based on the MDS, high (HP), medium (MP) and low (LP) productivity received mean SQI of 0.55, 0.48 and 0.39, respectively. The significant positive correlation between SQI and wheat yield suggests that this is a good representative of the MDS for the wheat-maize cropping system in China. We conclude that our SQI may be an effective and practical tool to guide a strategic, regional goal with respect to sustainable high yields. [ABSTRACT FROM AUTHOR]

Bio-fertilizers are thought to be overwhelmingly superior to chemical fertilizers for the improvement of soil quality and productivity. However, the comprehensive effects of bio-fertilizer on the soil ecosystem and the possibility of using multiple soil beneficial biota are still not well understood. A two-year field study was conducted to examine how crop yield, soil biochemical properties, enzyme activities, and functional diversity responded to different bio-fertilizers in the sweet potato phase of a double-cropping system (sweet potato and rapeseed). Six fertilizer treatments, including one chemical treatment (CF), two organic treatments (OM, organic manure; MC, organic manure plus chemical fertilizer) and three bio-fertilizer treatments (MCN containing nematodes, MCE containing earthworms, and MCP containing phosphate-solubilizing bacteria) were compared. The soils under CF had the lowest values for all soil parameters in comparison with the other treatments. Among the organic and bio-fertilizer treatments, OM performed better in improving soil biological properties such as soil respiration and microbial biomass, while soils under all these treatments had similar soil enzyme activities and functionality. Crop yield was positively correlated with soil nutrient levels, microbial biomass and enzyme activity, and most of the biochemical variables were highly intercorrelated. Our results indicated that organic fertilizers and bio-fertilizers were superior to chemical fertilizers and generally improved soil quality and productivity to similar levels in the field. [ABSTRACT FROM AUTHOR]

As a practical manner for improving soil quality, controlling pathogens and pests, and promoting plant growth, vermicompost is increasingly used in agriculture during these decades. Compared with chemical fungicides, vermicompost exhibits a promising potential for controlling fungal plant pathogens for its effectiveness and environmental friendliness. While as a hotspot for isolating beneficial microorganisms, little is known about the mechanisms underlying the interactions between indigenous beneficial microbes and phytopathogenic fungi. In this study, ten plant pathogenic fungi were used to screen antagonistic bacteria from vermicompost. Then, the antagonistic bacteria were identified based on its morphological, physiological and biochemical characteristics, and 16S rDNA gene sequence analysis, the strain M29 which belongs to Bacillus subtilis showed the broadest spectrum of antifungal ability was selected. The antagonistic effect of the mixed volatile organic compounds (VOCs) released by M29 showed significant inhibitory activity against Botrytis cinerea (BC). Based on the GC–MS analysis, eleven VOCs including alcohols, acids, ketones, esters, ethers and hydrocarbons were identified, and the antifungal activity of purified compounds was tested against BC in different concentrations. 1-butanol, acetic acid butyl ester, 1-heptylene-4-alcohol and 3-methyl-3-hexanol completely inhibited the mycelia growth in vitro at a low concentration of 50 μL per dish, while furan-tetrahydro-2,5-dimethyl completely inhibited mycelia growth only at a high concentration of 100 μL per dish. Although 2,6-diisocyanato-1-methyl-benzene, 1-propoxy-2-propanol and benzophenone had limited antagonistic effects on suppressing mycelial growth, they could destroy normal hyphae morphology and induce mycelial fragmentation and crumpling as other prominent compounds. Through this study, we demonstrated that as a biocontrol agent, vermicompost can inhibited the development of fungal pathogens through the VOCs released by symbiotic microbes, which may promote more reasonable and effective utilizations of vermicompost in the future. [ABSTRACT FROM AUTHOR]

Organic amendments not only promote soil quality and plant performance directly but also facilitate the establishment of introduced microbial agents. A field experiment with a fully factorial design was conducted using three levels of vermicompost (without vermicompost, low dose of 15 Mg ha −1 and high dose of 30 Mg ha −1 ), with and without plant growth-promoting rhizobacteria (PGPR) to investigate their effects in a tomato – by spinach rotation system. Our results demonstrated that applying PGPR alone had no effect on soil properties and crop performance. Vermicompost enhanced the beneficial effects of PGPR on both soil and crop, with the extent of promotion depending on the dose of vermicompost and crop types. In the presence of vermicompost, PGPR significantly ( P < 0.05) reduced soil carbon and nitrogen but increased soil microbial biomass carbon and nitrogen. PGPR also significantly increased the yield of tomato and spinach under the low dose of vermicompost, but only significantly increased tomato yield under the high dose of vermicompost. There were strongly synergistic effects between vermicompost and PGPR on crop quality, with crop nitrate concentration being significantly decreased, while the vitamin C in tomato and soluble protein in spinach was significantly increased. Our results revealed the high potential of integrating vermicompost and microbial agents to substitute for regular chemical fertilization practices. [ABSTRACT FROM AUTHOR]

• Adding organic materials to chemical fertilizer enhances crop yield and soil quality. • Organic materials with part chemical fertilizer (ORC) is the best regimes. • Crop yield-soil quality balance respond variously to climate and soil conditions. • Biochar, organic fertilizer or ORC can promote sustainable agricultural development. The contradiction between rapid soil degradation and increased food demand is becoming increasingly prominent. Reasonable recycling of agricultural waste can affect soil productivity and environmental health, thus playing a crucial role in the sustainability of agricultural production. Through a meta-analysis of 160 studies in the region of upland double cropping in China, we evaluate crop yield and soil quality responses to organic amendments. Results indicated that soil quality index (17.6%–26.3%) and crop yield (6.0%–9.0%) were significantly increased by adding organic amendments to chemical fertilizer. Combination of organic materials with total chemical fertilizer (OTC) and with part chemical fertilizer (ORC) significantly increased the yield by 8.3% and 8.7% and soil quality by19.5% and 18.4%, respectively. However, application of organic materials alone (O) decreased yields (by −0.6%), but significantly increased soil quality (by 49.1%). On average, organic amendments resulted in higher crop yield and soil quality index, despite variability introduced by tillage regimes and conditions of soil and climate. Relatively larger positive effect in crop yield and soil quality occurred with mean annual precipitation >1000 and <600 mm, respectively. Additional analyses found that biochar, organic fertilizer or ORC can promote sustainable agricultural development via improving crop yields, soil quality, and reducing nitrogen losses. Our results provide the first systematic review of effect of the organic amendments on the balance between soil quality and crop yield. The findings suggest that impacts of adding organic amendments to chemical fertilizer may be used as the foundation for policies. However, the combined use of organic amendments and other farmland management practices still present an area that needs further research in order to promote sustainable development of agriculture. [ABSTRACT FROM AUTHOR]

• Organic input can improve soil quality by the interaction of soil properties. • Use animal-derived organic fertilizer had better soil quality than plant-derived. • AP, AN, GP and AK were selected as a minimum data set for evaluating soil quality. • Information from soil indicators is integrated into a standardization framework. • Appropriate methods of scoring and weighting are determined in the framework. Organic fertilizer applications can increase soil fertility and productivity and reduce chemical fertilizer use. However, few experimental studies have focused on effects of organic fertilizers on soil quality in a field ecosystem. The overarching goal of this study was to develop a soil quality index (SQI) for fertilization management in red soil farmland in China. The specific objectives were to determine 1) appropriate soil quality indicators, 2) a suitable weight assignment method (PCA, principal component analysis or MRA, multiple regression analysis) and 3) the optimal scoring function (standard or linear or non-linear). We analyzed 40 soil physical, chemical, biochemical and biological properties under nine fertilization treatments (CK (no fertilizer), CF (chemical fertilizer), RF (60% chemical fertilizer), CFS (chemical fertilizer + straw), RFS (60% chemical fertilizer + straw), CFB (chemical fertilizer + biochar), RFB (60% chemical fertilizer + biochar), RFP (60% chemical fertilizer + pig manure), RFV (60% chemical fertilizer + vermicompost)) as potential soil quality indicators. Principal component analysis and correlation analysis were applied to determine the indicators responsive to management and for the confirmation of the six SQIs. Available phosphorous, nitrogen, potassium and gram-positive bacteria were chosen as the minimum data set from the total of 40 soil indictors. Management of organic and inorganic fertilizers affected each soil property in different ways, and the index based on the minimum data set, calculated using standard scoring function and weight assignment method of multiple regression analysis, was most accurate and sensitive. Application of a pig manure or vermicompost significantly increased SQI values relative to other treatments, followed by straw or biochar treatments which were higher than a single application of chemical fertilizer. These results indicate that the addition of organic fertilizers will not only improve soil quality, but also enhance rapeseed and sweet potato yield compared to chemical fertilizers. Additionally, the SQI method can provide a practical and quantitative tool for the evaluation of soil quality. [ABSTRACT FROM AUTHOR]