自然降雨条件下不同施肥模式和耕作方式对坡耕地紫色土肥力质量的影响

为探讨自然降雨条件下不同施肥模式和耕作方式对坡耕地紫色土肥力质量的影响，通过采集监测时长为9年的径流小区径流和土样，测定了径流量、有机质、全氮、全磷、全钾、速效磷、硝态氮和铵态氮等指标，运用灰色关联法建立了土壤肥力质量评价指标体系，分析了土壤肥力水平与施肥模式、耕作方式之间的关系。结果表明：5种不同试验处理下，各土壤肥力因子均有不同程度下降，其中土壤硝态氮和铵态氮含量减少最为显著；评价土壤肥力的关联度逐年减小，横坡耕作单施化肥处理的多年平均关联度表现最大，对应的多年平均径流量最小；顺坡耕作方式下，农家肥和化肥配施处理的多年平均关联度最大，对应的多年平均径流量最小，对照处理则相反；多年平均径流量与多年平均关联度之间满足线性函数模型y=-0.000 2x+0.762 8（R²=0.748 4），随着径流量的增大，土壤肥力质量显著下降，二者呈负相关关系。横坡耕作下农家肥和化肥配施处理对于维持土壤肥力水平以及减少地表径流量效果最优。

Effect of soil fertility quality based on different fertilization and tillage patterns in slope cropland of purple soil under natural rainfall

In order to explore the effect of different fertilization modes and tillage patterns on the quality of purple soil fertility in sloping cultivated land under natural rainfall conditions, the runoff and soil samples were collected, which based on the research on the experimental data with 9 years from runoff plots. The runoff volume, organic matter, total nitrogen, total phosphorus, total potassium, available phosphorus, nitrate nitrogen and ammonium nitrogen were measured exposure to different fertilization modes and tillage patterns. The evaluation index system of soil fertility quality was established by grey correlation method, and the relationship between soil fertility level, fertilization modes and cultivation modes were analyzed. The results indicated that under the 5 different treatments, all soil fertility factors decreased in different degrees. Among them, the decrease of soil nitrate nitrogen and ammonium nitrogen was most significant. The correlation degree of soil fertility evaluation decreased year by year, and the average annual correlation degree of single cropping with chemical fertilizer under cross slope tillage was the largest, and the corresponding annual mean runoff was the smallest. Under sloping tillage, the average annual correlation of farm manure and chemical fertilizer treatment was the largest, and the corresponding annual average runoff was the smallest, and the control treatment was the opposite. The relation between the average runoff and the average correlation degree fitted linear model(y=-0.000 2x+0.762 8, R²=0.748 4), with increase of runoff, soil fertility quality significantly decreased. The treatment of cross slope tillage with farmyard manure and chemical fertilizer was better for maintaining soil fertility level and reducing surface runoff.