长期保护性轮耕对黄土旱塬粮田生产力影响机制研究

Conventional tillage is very commonly used to store soil water,to improve soil fertility and to increase crop yield during fallow period on rainfed grain crop fields in high plain and gully region of the loess plateau,but its effect were not good as expected. Conservation tillages,which includes no tillage and subsoiling with crop residure mulching,can retain rain water in soil,return crop residure in field,decrease soil erosion and increase crop yield in drought environment. But continously keep using mono-tillage measures of no tillage or subsoiling on rainfed grain fields in long-term period, its disadvantages of compacted soil structure and nutrition enriching in top soil layer is increasing significantly. On rainfed grain fields in high plain and gully region of the loess plateau,to study long-term rotation patterns of conservation tillages and its effects,which combined with no-tillage or subsoiling with crop residure mulching, and deep plowing with crop residure buried into soil, is very important to enhance ability of drought resistant,soil quality improvement and yield increasing on rainfed grain fields.A long term field experiment of conservation tillage rotations on rainfed grain field of Weibei highland, Shaanxi province， will be continuously conducted, and WinEPIC model will be used to simulate soil water and nutrition changes and crop yield response quantitatively under different rotational patterns of conservation tillages on Weibei highland of the loess plateau during very long period, to explore its effects on soil water restoration, soil quality improvement,and crop yield increasing with cost reduction and as well as its differences between different grain cropping systems, to choose the optimal rotational patterns of conservation tillages on grain fields for different grain cropping systems to increase high-use-effeiciency of soil water and fertilizer, in order to obtain high and sustainable crop yield, and can supply scientific foundation for high yield and high benefit of rainfed grain fields sustainablly on high plain and gully region of the loess plateau.

黄土旱塬区粮田长期盛行休闲期土壤翻耕制，其抗旱、培肥和增产效果较差。秸秆覆盖免耕和深松等保护性耕作有利于降水贮蓄、秸秆还田、减缓侵蚀和抗旱增产，但长期连续实施单一秸秆覆盖免耕或深松，易导致土壤结构紧实、表层养分富集等弊端凸显。研究由秸秆覆盖免耕、秸秆覆盖深松和秸秆还田翻耕等保护性耕作措施组成的轮耕模式及其效应，有利于持续增进旱作粮田抗旱、培肥和增产能力。通过渭北旱塬冬小麦连作田、春玉米连作田和麦玉轮作田长期保护性耕作定位试验和WinEPIC模型长周期定量模拟，研究黄土旱塬区不同轮作类型粮田在不同保护性轮耕模式（秸秆覆盖免耕、秸秆覆盖深松和秸秆还田翻耕三者组合）下的土壤水肥动态和作物产量响应，揭示各类保护性耕作轮耕模式的蓄水保墒机理、土壤培肥规律和增产节本效应及其轮作茬口差异，筛选与确定黄土旱塬区水肥高效利用和高产稳产高效型的保护性耕作轮耕模式，能为黄土旱塬粮田可持续高产高效提供科学依据。

针对黄土旱塬区粮田休闲期长期连续实施翻耕、免耕和深松等单一耕作措施所致弊端，基于2007-2019年陕西渭北旱塬合阳县冬小麦连作田、春玉米连作田和麦玉轮作田长期保护性耕作定位试验和1980-2009年WinEPIC模型长周期定量模拟，研究由秸秆覆盖免耕、秸秆覆盖深松和秸秆还田翻耕等耕作措施组成不同保护性轮耕模式的蓄水保墒、土壤培肥和增产增收效应。综合分析2007-2019年连续12年长期保护性耕作定位试验作物产量、水分利用效率、土壤碳氮含量变化动态数据，冬小麦连作田以“翻耕/翻耕/深松轮耕”或“免耕/免耕/深松轮耕”模式、春玉米连作田以“免耕/翻耕/深松轮”耕模式、麦玉轮作田以“翻耕/免耕轮耕”模式的节水、培肥、增产和增收效果最好，各轮耕处理12年平均产量分别为小麦3965或3896 kg•hm-2、玉米8935 kg•hm-2、小麦5043 kg•hm-2和玉米6540 kg•hm-2。基于1980-2009年连续30年长期保护性耕作效应定量模拟结果表明，连作麦田以“免耕/深松轮耕”处理产量最高，平均值为3.53 t hm-2，WUE以“免耕/免耕/深松”处理和“免耕/翻耕/深松轮耕”处理较高，30年平均值WUE均为8.68 kg•hm-2•mm-1；麦玉轮作田以“常规施肥+翻耕/免耕轮耕”处理作物产量和WUE较高，分别为5.65 t•hm-1和14.59 kg•hm-1•mm-1，以“平衡施肥+翻耕/免耕轮耕”处理土壤有机碳含量较高，其增产保墒固碳效果较好。所筛选出的水肥高效利用和高产稳产高效型的保护性耕作轮耕模式，为黄土旱塬粮田可持续高产高效提供了科学依据。项目执行期间，发表期刊论文17篇和会议论文3篇，其中SCI论文9篇，EI论文1篇；培养研究生12人，其中博士生4人；发布陕西省地方标准2项。