水源保护区坡耕地不同种植模式水土保持效应试验

在水源保护区16．5°的坡耕地上，通过3种种植模式（玉米＋小麦、牧草混播、黄梨＋绿肥）进行连续3年水土保持试验，研究水源保护区坡耕地水土保持效应。结果表明：1）与玉米＋小麦习惯轮作模式相比，牧草混播及黄梨＋绿肥种植模式降低径流量、土壤流失量、养分流失量分别为27．7％、44．2％、38．0％及14．4％、20．9％、27．9％，牧草混播及黄梨＋绿肥2种种植模式都能有效地降低水土及养分流失，并且效果随着年限延长而增加；2）在肥料施用量比玉米＋小麦种植模式减少34．0％的条件下，牧草混播种植模式的纯收益仍能与玉米＋小麦轮作模式持平；黄梨＋绿肥种植模式纯收益比玉米＋小麦种植模式提高5．9％，梨树盛果期以后，产值还有很大提升空间；3）从水土保持角度看，牧草混播种植模式的效果最好，从经济角度分析，黄梨＋绿肥种植模式效益最高，二者都可作为水源保护区种植结构调整及坡耕地综合治理的较好模式。

Soil and water conservation effects of different cropping patterns in slope croplands in water conservation areas

The effects of soil and water conservation by three cropping patterns （Zea mays L. plus Triticum aestivum crop rotation, multiple forage seeding pattern, and Pyrus sorotina plus green manure pattern） were studied in slope croplands of 16.5~ in water conservation areas. The three-year monitoring data showed that, compared with the Zea mays L. plus Triticum aestivum crop rotation, the multiple tbrage seeding pattern could effectively decrease the soil erosion and nutrient loss, the volume of runoff, soil loss and nutrients loss by 27.7% , 44.2% and 38.0% , respectively, while the Pyrus sorotina plus green manure pattern decreased these indexes by 14.4% , 20.9% and 27.9% , respectively, and the effects were strengthened over time. In comparison with the Zea mays L. plus Triticum aestivum crop rotation, the multiple forage seeding pattern could still gain equivalent net income even when reducing the application of＇ fertilizers by 34.0%. The net income of Pyrus sorotina plus green manure pattern increased by 5.9% compared with the Zea mays L. plus Triticum aestivum crop rotation. In addition, the Pyrus sorotina yield still has great potential to rise after full productive period. From the perspective of soil and water conservation, the multiple forage seeding pattern has the best effects; while from the economic point of view, the Pyrus sorotina plus green manure pattern produces the highest benefit. Both of them can be considered as optimum schemes to modulate the cropping patterns and manage slope croplands comprehensively in water conservation areas.