宁南半干旱区沟垄二元覆盖条件下土壤水-温-肥联动效应研究

The semi-arid areas of southern Ningxia is located in northwest of Loess Plateau, China, and it has the drought climate. Low temperature and precipitation deficiency during the early growing season, and higher temperature during the later growing season are main factors limiting crop productivity in this region. Therefore, the potato which is widely planted in this region as tested crop, we design the planting experiment of different ridge-furrow ratios and mulching materials in the furrow, from the perspective of optimizing water and temperature environment of the farmland, and improving the rainwater use efficiency. We study the spatial and temporal changing rules of soil water, temperature, and nutrient under dual-mulching of ridge-and-furrow, to prove up the mechanism of temperature adjusting, moisture conserving, and the response mechanism of soil nutrient to soil water and temperature changes under the dual-mulching of ridge-and-furrow. Taking the growth and yield of potato as a case, the research will clarify the influence of soil water and temperature, fertility coupling effect with dual-mulching of ridge-and-furrow, and determine proper pattern of dual-mulching of ridge-and-furrow in arid and semi-arid area, to provide a theoretical guidance for the cultivation technique with rainwater harvesting and water conservation in dryland.

宁夏南部半干旱区位于黄土高原西北部，气候干旱。作物生长前期气温较低、降水较少、后期气温高是制约该区作物产量提高的主要因素。因此，本研究以当地主栽作物马铃薯为研究对象，从优化农田水热环境、提高自然降水利用率的角度出发，设置不同沟垄比和沟内覆盖材料的种植试验，研究不同沟垄二元覆盖模式下土壤水分、温度、养分时空变化规律，探明其调温保墒机制及土壤养分对水温变化的响应机理。以马铃薯生长和产量表现为实证，揭示沟垄二元覆盖模式下土壤水-温-肥的联动效应，确定适宜宁南半干旱区的垄沟二元覆盖模式，为集雨保墒旱作栽培技术提供理论指导。

宁南半干旱区作物生长前期降水少、后期气温高是限制马铃薯产量提高的关键因素。本项目将沟垄比与沟垄覆盖模式相结合，连续四年研究沟垄二元覆盖条件下土壤水-温-肥联动效应，以马铃薯生长和产量表现为实证，确定适宜宁南半干旱区的垄沟二元覆盖模式。研究结果表明，整个生育期垄侧和垄上土壤蓄水量以垄覆地膜沟覆秸秆处理（DJ）最高；垄中生育前期以垄覆地膜沟覆可降解渗水地膜处理（DS）最高，中后期以DJ处理较高。垄覆地膜沟覆地膜处理（DD）整个生育期0~25 cm层垄侧、垄中增温效果显著，垄覆地膜沟覆纤维膜处理（DM）前中期增温效果显著，而DS、DJ处理前中期降温效果显著。垄上各覆盖处理均表现为显著增温。生育期土壤蓄水量随垄宽的增加而增加，各覆盖处理土壤蓄水量以DJ和DM处理表现最佳。沟垄比60 cm:45 cm下土壤增温效果较好，各覆盖处理以DD和DS处理表现最佳；DJ处理可降低土壤温度，且随垄宽的增加而降低。不同沟垄二元覆盖模式下收获期0-60 cm层土壤养分含量随垄宽增加而减小。土壤有机质以DJ和DM处理最高，土壤全氮、全磷、全钾、硝态氮、铵态氮、速效磷和速效钾含量均以DD和DJ处理最高。土壤易氧化有机碳含量以60 cm: 45 cm沟垄比最高；同一沟垄比下以DM处理表现最佳。0-40 cm层土壤微生物量碳、氮含量均以DJ和DM处理表现最佳；沟垄比间以60 cm:45 cm最高。土壤有机碳累积矿化量、矿化速率均随垄宽的增大而增大。同一沟垄比下以DM处理表现最高。沟垄二元覆盖模式可提高马铃薯植株养分的吸收，以DJ处理效果最佳。随垄宽的增加净光合速率、气孔导度和胞间CO2浓度均有所增加，各覆盖处理以DD和DM表现最佳。60 cm:45 cm沟垄比光合势较高，各处理以DD和DM处理最为显著。沟垄二元覆盖可降低可见光辐射透射率和反射率，均表现出较高的光能截获与利用效率。马铃薯生长以DS和DD处理表现最佳，马铃薯产量随垄宽的增加表现为先增加后下降，在60 cm:45 cm沟垄比下DM、DS和DD处理马铃薯增产增收效果较好。从环保角度考虑，DM和DS处理具有替代传统地膜的潜力优势。本项目研究结果在宁南旱作马铃薯高产栽培中具有重要的推广应用价值。