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Straw mulching has been used to conserve soil water and sustain dryland crop yields, but the impact of the quantity and time of mulching on soil C fractions are not well documented. We studied the effects of various amounts and times of wheat (Triticum aestivum L.) straw mulching on soil C fractions at 0–10- and 10–20-cm depths from 2009 to 2017 in the Loess Plateau of China. Treatments were no mulching (CK), straw mulching at 9.0 (HSM) and 4.5 Mg ha−1 (LSM) in the winter wheat growing season, and straw mulching at 9.0 Mg ha−1 in the summer fallow period (FSM). Soil C fractions were soil organic C (SOC), particulate organic C (POC), microbial biomass C (MBC), and potential C mineralization (PCM). All C fractions at 0–10 and 10–20 cm were 8–27% greater with HSM and LSM than FSM and CK. Both SOC and POC at 0–10 cm increased at 0.32 and 0.27 Mg ha−1 year−1 with HSM and at 0.40 and 0.30 Mg C ha−1 year−1 with LSM, respectively, from 2009 to 2017. Winter wheat grain yield was lower with HSM and LSM, but total aboveground biomass was greater with HSM than other treatments. All C fractions at most depths were correlated with the estimated wheat root residue returned to the soil and PCM at 0–10 and 0–20 cm was correlated with wheat grain yield. Wheat straw mulching during the growing season increased soil C sequestration and microbial biomass and activity compared with mulching during the fallow period or no mulching, regardless of mulching rate, due to increased C input, although it reduced wheat grain yield. Continuous application of straw mulching over time can increase soil C sequestration by increasing nonlabile C fractions while decreasing labile fractions. Straw mulching at higher rate and mulching during the summer fallow period had no additional benefits in soil C sequestration.

Soil microbial necromass carbon (C) is a crucial component of the soil organic C pool. The impact of both straw mulching treatments and years on the soil microbial necromass C accumulation remains unclear. We investigated factors driving soil microbial necromass C accumulation and its role in improving yield by analyzing the dynamic response of microbial necromass C, total organic C (TOC) and available nutrients, genes encoding carbohydrate-degrading enzymes and fruit yield of citrus under different straw types of mulching (wheat, rice, oilseed rape, no mulch) from 2019 to 2022. Annual rainfall was the main factor affecting the soil bacterial necromass C (BNC) accumulation. Straw mulching treatments were the main factor affecting the soil fungal necromass C (FNC) accumulation. Increased annual rainfall and high soil moisture levels hindered the soil microbial necromass C accumulation, especially BNC. No correlation was found between BNC and the relative abundance of genes encoding peptidoglycan (bacteria-derived biomass) degrading enzymes. Decreased relative abundance of genes encoding chitin (fungal-derived biomass) degrading enzymes, particularly GH18, favored the accumulation of FNC. Actinomycetes were the most significant contributors of the GH18 gene among microbial phyla. Moreover, oilseed rape and rice mulching treatments reduced the relative abundance of genes encoding enzymes degrading chitin. Microbial necromass C, especially BNC, was key for sustaining TOC, supplying nutrients, and enhancing citrus fruit yield. Our results provide new information for optimizing straw mulch type and application time in citrus orchards to improve soil microbial necromass accumulation.

【Objective】 The purpose of this paper is to give full play to the respective advantages and synergistic effects of straw mulching and suitable irrigation on crop yield and soil carbon sequestration and emission reduction, establish an efficient farmland management mode of emission reduction, increase, and water saving. 【Method】 Taking summer maize in Western Henan as the research object, the mulching method and the lower limit of irrigation water were tested. The mulching method was straw mulching (S) and no mulching (N). The lower limit of irrigation water was set at four levels: 50% (W1), 60% (W2), 70% (W3) and 80% (W4) of field water holding capacity. Soil respiration, crop biomass and grain yield under different treatments were systematically studied. The total amount of soil carbon emission, the amount of soil microbial isooxygen respiration carbon release and the amount of carbon sequestration of farmland net primary productivity were calculated. Farmland net ecosystem productivity (NEP) was calculated as the carbon sequestration of farmland net primary productivity and the carbon release of soil microbial iso-respiration. Carbon emission efficiency (CE) calculated from crop yields and soil carbon emissions reflected the economic and environmental benefits of farmland. NEP and CE were used to objectively evaluate the effects of straw mulching and different irrigation lower limits on crop yield and carbon sequestration. 【Result】 The soil respiration rate of SW4 treatment was the highest and that of NW1 treatment was the lowest. Soil respiration rate of SW4 treatment reached the highest value at anthesis stage 6.08 μmol/(m2·s), and there was no significant difference between SW3 treatment and NW4 treatment. Compared with NW1 treatment, straw mulching and irrigation increased the amount of carbon sequestration in farmland net primary productivity and the amount of soil microbial iso-respiratory carbon release, and that of SW4 treatment was the highest, with no significant difference compared with SW3 treatment and NW4 treatment. SW3 treatment had the highest NEP which was 3.99%-245.74% higher than that of other treatments and the highest CE which were 2.35%-138.80% higher than that of other treatments. Compared with SW4 treatment, NEP of SW3 treatment increased by 2.99% and CE of SW3 treatment increased by 2.35% under the premise of saving irrigation. 【Conclusion】 The lower limit of irrigation water is 70%FC and straw mulching (SW3) treatment, which can effectively coordinate the yield and carbon emission efficiency of summer maize farmland system, promote higher crop yield, achieve higher net ecosystem productivity and carbon emission efficiency, and reduce the carbon emission generated in the production process under the condition of higher irrigation amount. Achieve carbon sequestration and emission reduction and water utilization system promotion. Considering net ecosystem productivity and carbon emission efficiency of farmland, SW3 treatment can be used as a farmland management mode for water saving, emission reduction and yield increase.

Taking sustainable agriculture measures is critical to effectively cope with the effect of the increasing population on water shortage. Straw mulching and reduced tillage are the most successful measures adopted in arid and semi-arid regions which affect crop production by changing the crop environment. This review focuses on the effects of tillage and mulching on the soil environment, including soil organic matter, soil moisture, soil temperature, soil microorganisms, soil enzyme activity, soil fertility, soil carbon emissions, pests, weeds, and soil erosion. In addition, water use efficiency and crop production are discussed under different tillage measures. Straw mulching can increase soil organic matter content, adjust soil moisture, and prevent water loss and drought; however, it can also lead to an increase in pests and diseases, and change the structure of the soil microbial community. Straw mulching can significantly enhance WUE (water use effectively) and yield. Reducing tillage maintains soil integrity, which is conducive to soil and water conservation, but could negatively impact crop yield and WUE. Precise field management measures, taken according to crop varieties and local conditions, not only ensure the high yield of crops but also protect the environment.

【Objective】 Straw mulching and ridge tillage is an improved agronomic technology to sustain crop production in the loess plateau in northwestern China. How their combination impacts water uptake and crop yield is not well understood. This paper is to fill this knowledge gap. 【Method】 The experiment was conducted in a potato field and compared ridge tillage and traditional flatten tillage. For the ridge tillage, there were three mulching treatments: film mulching (PM), locally high straw mulching (RSM9), and locally low straw mulching (RSM6). For the traditional flatten tillage, there were also three treatments: locally high straw mulching (PSM9), locally low straw mulching (PSM6), and full straw mulching (FC). The control is flatten tillage without mulching. 【Result】 ①Compared with CK, mulching increased the yield and WUE of the potato by 11.8% 21.7% and 15.9% 26.7%, respectively. Compared with PSM treatments, RSM treatments increased the yield and WUE of the potato by 1.5% and 1.7%, respectively. Compared with the locally high straw mulching (9 000 kg/hm2), the locally low straw mulching (6 000 kg/hm2) increased the yield and WUE by 6.1% and 6.5%, respectively. ② Compared with CK, local straw mulching increased soil moisture in some regions and reduced it in other regions, but overall, it increased soil water content. The increased soil water storage under different treatments was ranked in the order of RSM6 >PSM6 >RSM9 >PSM9 treatment. ③ Compared with CK, partial straw mulching increased total water consumption, daily water consumption, and water consumption coefficient for potato tuber formation and starch accumulation by 4.6 mm, 0.11 mm/d and 2.7%, respectively. Water consumption during tuber expansion and harvest was greater in RSM than in PSM, while the opposite was true during soil-tuber expansion. 【Conclusion】 Straw mulching can reduce water consumption before tuber expansion, increase water consumption after tuber expansion, balance water consumption and demand during key growth stages, and promote potato growth and development. For all treatments we compared, ridge tillage coupled with partial straw mulching at 6 000 kg/hm2 was most effective.

The utilization of crop straw is important for the green development of agriculture and the ecological environment. China’s agricultural planting structure is diversified and straw utilization has received increased attention. Here, in situ experiment with four types of crop straw (i.e., straw of oilseed rape, wheat, rice and corn) was conducted to analyze the effects of climate factors (i.e., accumulated temperature, AT) and straw returning methods on straw decomposition and the release of nutrients. The AT value was an important factor affecting straw decomposition and carbon, nitrogen, and phosphorus release. When straw was incorporated into the soil, the straw decomposition rate could be stimulated when the AT ≥ 600–740 °C. Under straw mulching, the decomposition rate could be further enhanced if the AT exceeded 960–1300 °C. At the end of the experiment, the decomposition and nutrient release rates increased by 39.7–148.7% and 5.8–171.5%, respectively, under straw incorporation compared to straw mulching. The differences under different returning methods in straw decomposition and nutrient release rates were higher in the summer–autumn stage (114.3–148.7% and 14.7–171.5%) than in the winter–spring stage (39.7–47.6% and 5.8–62.5%). The variance in the C/N ratio and the infrared characteristic peak of different straw types affected the decomposition rate and nutrient release characteristics. This study concludes that straw decomposition and nutrient release varied widely among different AT values, straw types, and returning methods.

Background: Mulching and burnt wood treatments are commonly applied to prevent the loss of soil quality and erosion, but their effect on soil multifunctionality remains unexplored.Aims: We filled this gap by assessing the medium-term (4 years) effects of these treatments on soil multifunctionality after a large wildfire in NW Spain.Methods: Straw mulching (SM) and cut plus lopping (CpL) treatments were applied in high-severity affected areas of heathland plant communities. CpL areas had been afforested with Scots pine 15 years before the fire. We considered four soil functions estimated in treated and burned control plots 4 years after fire: (1) carbon regulation; (2) water regulation; (3) soil fertility; and (4) nutrient cycling. The functions were integrated into a multifunctionality index and linear models were used to evaluate treatments effect.Key results: SM had no impact on individual functions and multifunctionality. Conversely, CpL with burnt Scots pine wood was able to sustain higher levels of multiple functions simultaneously than control areas. Consistent trade-offs between soil functions emerged in control areas for both treatments.Conclusions: Burnt wood could ensure long-lasting effects to promote soil multifunctionality in Mediterranean ecosystems.Implications: We recommend using a multifunctionality approach to avoid biases in treatment success.

Crop straw mulching is an important organic supplement in sustainable agriculture; however, the effect of increased organic matter on the diversity of micropredators such as myxobacteria and the correlation between myxobacteria and microorganisms have been little explored. In the current investigation, high-throughput sequencing was performed to analyze the myxobacterial community composition in a wheat-corn rotation experimental field with 6-year straw mulching and fertilization treatments. The results reveal no significant influence of straw mulch application on myxobacterial α-diversity ( P  < 0.05). NMDS (nonmetric multidimensional scaling) and perMANOVA results indicate the significant influence of straw mulching application on myxobacterial community composition ( P  < 0.05), and several groups, including Haliangiaceae , Polyangiaceae , and Archangiaceae , also varied in soil aggregates. RDA (redundancy analysis) results show that TOC (total organic carbon) was the most important factor affecting the myxobacterial community structure. In addition, RDA and random forest analysis results show the contribution of myxobacterial community structure to soil bacterial community α- and β-diversity, especially in the 0.25–1 mm and < 0.25 mm soil aggregate fractions. In conclusion, we suggest that the variation in myxobacterial community structure may be a driver of bacterial α- and β-diversity in soil microhabitats and might be a cause of soil microbial community changes. Our results are fruitful for finding more efficient ways to use straw from waste for the betterment of sustainable agriculture by analyzing changes in myxobacterial community structure.

PurposeSoil fertility plays a key role in citrus productivity. Therefore, it is necessary to explore the effects of soil amendments on soil fertility and citrus productivity and estimate carbon fractions’ suitability, which response to soil fertility and citrus productivity.MethodsA field experiment in a citrus orchard was conducted containing five treatments: local habit fertilization (LF), special fertilizer [25% lower NPK than LF, (SF)], special fertilizer, and rice straw mulching [0%, 12.5%, and 25% NPK higher than LF (SFRS25, SFRS37.5, and SFRS50, respectively)]. Total organic carbon (TOC), microbial biomass carbon (MBC), water-soluble organic carbon (WSOC), permanganate oxidizable carbon (ROC), available N, P, K, fruit yield, and quality were analyzed.ResultsStraw mulching and special fertilizer significantly increased soil carbon fractions, such as MBC and ROC. Such treatments also enhanced the soil available N, P, and K, subsequently elevated the fruit yield. MBC, available K, and available P showed a significantly positive correlation with citrus yield. Redundancy analysis indicated that MBC and ROC significantly explained 61.87% of the variation for available nutrients, suggesting that the increase of organic carbon fractions and microbial biomass could accelerate nutrient cycling for the plant.ConclusionIt proved that decrement application of special compound fertilizer with straw mulching raised fruit yield by altering soil carbon fractions to improve soil available nutrients or fertility. The MBC of soil labile carbon responded more sensitively to not only soil fertility but also citrus fruit yield.