农业生态系统养分循环再利用作物产量增益的地理分异

Geographic differentiation of yield increase efficiency caused by recycled nutrients in agro ecosystems.

通过４个地点中长期田间试验联网比较获得以下结果，农业生态系统养分循环再利用的作物产量增益受气候的热量因素、化肥施用和养分循环再利用持续时间的长短等因素影响．在不施化肥情况下，保持０．８循环率养分循环再利用的平均粮食增产量自北向南分别是：温带黑龙江海伦２５３ｋｇ·ｈｍ－２（１０年平均）、暖温带辽宁沈阳１１２２ｋｇ·ｈｍ－２（６年）和喀左１３３２ｋｇ·ｈｍ－２（８年）、亚热带湖南桃源２８８４ｋｇ·ｈｍ－２（７年）；在施用ＮＰ化肥基础上保持养分循环再利用则分别为海伦２２５、沈阳６９４、喀左７８６、桃源１３２１ｋｇ·ｈｍ－２．循环回田的农家肥养分对作物增产有着明显的残效叠加作用，在施用ＮＰＫ化肥基础上保持养分循环再利用的作物增产率在试验期间的前３年平均为５％，后３年平均可上升至１４％．

The results of field experiments at four stations in different parts of China indicate that the crop yield increment caused by recycled nutrients within an agricultural ecosystem was significantly influenced by the thermal condition of climate, the application of fertilizers and the duration of the experiments lasted. In the case of no fertilizer, the average crop yield increment caused by recycled nutrients with a 0.8 recycling rate ranged from 253kg·hm -2 (average of ten years) at Hailun station (in temperate zone ) to 1122kg·hm -2 (six years) at Shenyang station and 1332kg·hm -2 (eight years) at Kezuo Xiahetao station (in warmer-temperate zone), and to 2884kg·hm -2 (seven years) at Taoyuan station (in subtropical zone), while on the base of applying N and P fertilizers, the corresponding increments at the four stations were 225, 694, 786 and 1321kg·hm -2 respectively. There was a marked accumulative residual effect of recycled nutrients in farmyard manure on crop yields,based on N, P and K fertilizers, the average increase rate of crop yields caused by recycled manure was about 5% in the first three years, but raised up to about 14% in the last three years within the experimental period.