[Effects of long-term no-tillage and stover mulching on maize yield and its stability.] / é•¿æœŸå è€•ä¸åŒç§¸ç§†è¦†ç›–é‡å¯¹çŽ‰ç±³äº§é‡åŠå ¶ç¨³å®šæ€§çš„å½±å“.

Clarifying the differences of maize yield and its stability under long-term no-tillage with different stover mulching amounts can provide theoretical and technical supports for establishing and evaluating long-term conservation tillage pattern and promoting grain production. Based on a long-term conservation tillage field experiment in the mollisol area of Northeast China since 2007, we analyzed the interannual variation, variation coefficient and stability of maize yield during 2013 and 2019 across five treatments, i.e., no-tillage stover-free mulching (NT0), no-tillage with 33% stover mulching (NT33), no-tillage with 67% stover mulching (NT67) and no-tillage with 100% stover mulching (NT100), with the traditional ridge cropping (RT) as the control. The results showed that compared with RT, long-term no-tillage with stover mulching treatments could increase maize yield. NT100 had the highest increasing rate of 11.4%, followed by NT67 and NT0, with the increasing rate of 11.0% and 10.4%, respectively. Maize yield exhibited a nonlinear relationship with the amount of stover mulch. The variation coefficient of maize yield under multi-year no-tillage with different stover mulching could be sorted as NT67NT0>NT100>RT>NT33, indicating that NT67 treatment could significantly reduce the interannual fluctuation of maize yield and had better sustainability of yield. No-tillage stover mulching significantly increased soil total carbon and total nitrogen contents, which were significantly positively correlated with maize yield. In conclusion, compared with traditional tillage, no-tillage stover mulching could increase maize yield and soil carbon and nitrogen contents. Appropriate stover mulching (NT67)had the potential to improve the stability and sustainability of maize yield.

[Research advances on cover crop plantation and its effects on subsequent crop and soil environment]. / è¦†ç›–ä½œç‰©çš„ç§æ¤çŽ°çŠ¶åŠå ¶å¯¹ä¸‹èŒ¬ä½œç‰©ç”Ÿé•¿å’ŒåœŸå£¤çŽ¯å¢ƒå½±å“çš„ç ”ç©¶è¿›å±•.

Cover crops are grown in temporal and spatial gaps of agricultural production to reduce or avoid soil exposure. As it can protect farmland soil from wind erosion, water erosion and human disturbance, planting cover crops is considered as a new type of conservation tillage practice. Here, we briefly introduced the planting management of cover crops, including crop species, planting modes, and the returning to farmland after their termination, which could provide a reference for efficiently planting cover crops at large scale during the fallow period. Based on domestic and foreign studies, we summarized the benefits of cover crops on agroecosystem, including cash crops, soil quality, weed control, greenhouse gas emission, and soil microbes. Our review illustrated their importance in improving soil quality and achieving sustainable agricultural development, despite the limitation of cover crops, including unobvious benefits in the short-term and the reduction of crop yield caused by improper management.

[Effects of corn stover mulch quantity on mid-infrared spectroscopy of soil organic carbon in a no-tillage agricultural ecosystem]. / çŽ‰ç±³ç§¸ç§†è¦†ç›–è¿˜ç”°é‡å¯¹å è€•åœŸå£¤æœ‰æœºç¢³ä¸­çº¢å¤–å ‰è°±ç‰¹å¾çš„å½±å“.

We examined carbon chemical composition and stability along soil depth (topsoil 0-5 cm, mid-soil 20-40 cm, and deep soil 60-100 cm) in a no-tillage (NT) agricultural system with various amount of corn stover as mulch for 8 years, including 0 (NT0), 33% (NT33), 67% (NT67) and 100% (NT100), in Northeast China, using mid-infrared spectroscopy. The results showed that, relative to NT0, the treatments of NT33 and NT100 increased polysaccharide content of the top layer and mid-layer soils, the former decreased topsoil carbon component diversity, while the latter maintained soil carbon stability of three soil layers. NT67 increased carbon stability at the deep layer soil. Our results demonstrated that if corn stover resources were sufficient, NT with 100% corn stover mulch could both be beneficial to carbon availability at 0-40 cm soil layer and stability of the whole soil profile. The nonlinear relationship between the amount of corn stover mulch and the mid-infrared spectral characteristics of the soil called for further research on the microbial-control mechanism over soil carbon cycling under different amounts of corn stover mulch.

[Effects of different fertilization managements on microbial necromass and plant lignin accumulation in a Mollisol]. / 不同施肥管理措施对农田土壤中植物和微生物残留组分的影响.

Fertilization is an effective management to maintain and increase soil organic carbon (SOC) level in agroecosystems. Both microbial metabolism and plant component retention control SOC sequestration. Here, we used amino sugars and lignin as biomarkers to investigate the responses of distribution of microbial necromass and plant debris in a long-term cultivated soil (30 years) and SOC accumulation to different fertilization regime. The results showed that, compared with unfertilized treatment, inorganic fertilizer application (N fertilizer-only or the combination of organic or inorganic fertilizers) increased crop production and soil amino sugar accumulation, but did not affect the concentrations of lignin and SOC, indicating that inorganic fertilizer stimulated the assimilation of microbial substrate and accelerated the turnover of SOC and lignin in the plough layer. Compared with inorganic fertilizer treatment, long-term organic fertilizer application promoted SOC accumulation (38.3%), but did not affect amino sugar concentration in SOC, which indicated that soil could reach a 'saturation' state with respect to microbial residue accumulation. In contrast, the application of organic fertilizer increased the proportion of lignin in SOC,indicating that the contribution of plant residues to SOC persistence was enhanced. Compared with the manure-only treatment, organic-inorganic combined application mainly increased the contribution of amino sugar to SOC accumulation. Our findings indicated that long-term fertilization could affect SOC dynamics through modulating the accumulation processes of microbial necromass and plant debris.

[Effects of different straw returning amount on the potential gross nitrogen transformation rates of fertilized Mollisol.] / ç§¸ç§†è¿˜ç”°é‡å¯¹åŸ¹è‚¥å†œç”°é»‘åœŸæ°®ç´ åˆçº§è½¬åŒ–é€ŸçŽ‡çš„å½±å“.

Straw returning is one of the important measures for improving soil fertility. It is unclear, however, whether the regulation function of soil on nitrogen (N) cycle after fertilization is sustainable and the relationship between the regulation function and the amount of straw returned to the field. In this study, a 3-year straw returning field trial was set up in a field had been carried out straw returning of all the havested straw for nine years. The amount of straw returned was 100%, 67%, 33% and 0 of the average annual straw yield (7500 kg·hm-2) to identify the effects of different straw returned amount on N transformation in the fertilized soil (0-10 cm). Results showed that the amount of straw returning affected the production and consumption of NH4+-N and NO3--N by affecting the potential gross N transformation rate. When the amount of straw returning was less than 67%, the production rate of NH4+-N significantly reduced and the consumption rate significantly increased, and thus led to the decrease in soil NH4+-N retention capacity. The NO3--N production rate increased and the retention capacity decreased, and the NO3--N accumulation and leaching loss risk increased. Therefore, returning more than 67% of harvested straw was necessary to maintain the function of soil N conservation.