免耕措施下黑土区坡耕地土壤肥力质量评价

以东北黑土区坡耕地为研究对象,采集不同坡位(坡上位、坡中位、坡下位)深度(0～10、10～20 cm)土壤,研究免耕措施下土壤理化性状及土壤酶活性不同坡位变化情况,并用因子分析和土壤质量指数法综合评价土壤肥力质量。结果表明,免耕后各坡位土壤容重减小,土壤孔隙度扩大,全氮、有机质和速效钾含量增加,土壤脲酶、过氧化氢酶和蔗糖酶活性呈升高趋势。随坡面向下,土壤容重呈减小趋势,土壤孔隙度、田间持水量和土壤含水量呈增大趋势。土壤全氮和有机质含量在不同坡位差异显著(P<0.05),主要集中在坡中位和坡下位较高;土壤铵态氮、土壤硝态氮、土壤有效磷、土壤速效钾含量主要集中在坡上位和坡下位较高,而pH主要集中在坡中位较高。土壤脲酶和过氧化氢酶活性表现为坡上位和坡下位较高,蔗糖酶活性坡中位和坡下位较高。通过因子分析将14项土壤指标分为5个公因子,即土壤肥力、水分、结构、养分和生物学因子。利用土壤质量指数分析坡耕地耕层特征发现,免耕一年后各土层坡下位土壤质量指数高于坡上位和坡中位,免耕两年后各土层为坡中位和坡下位土壤质量指数高于坡上位,说明坡下位形成相对平衡和较高肥力质量的土壤。与免耕前相比,经两年免耕后坡中位土壤质量得到改善。

Soil fertility quality evaluation of slope farmland under no-tillage in black soil area

In this paper, the sloping farmland in the black soil area of Northeast China was taken as the research object, and soils were collected with different depths(0-10, 10-20 cm) at different slope positions(upper slope, middle slope, and lower slope) to study the changes of soil physical and chemical properties and soil enzyme activities at different slope positions under no-tillage measures.And factor analysis and soil quality index method were used to evaluate the soil fertility quality comprehensively. The results showed that, the bulk density of soil in each slope decreased after notillage. The soil porosity, the soil total nitrogen content, the soil organic matter and the soil available potassium content all increased after no-tillage. The soil urease activity, the soil catalase activity and soil sucrase activity all increased after no-tillage practice. The soil bulk density showed a decreasing trend with the slope down, and the soil porosity, field moisture capacity and soil water content showed an increasing trend. Soil total nitrogen and soil organic matter content were significantly different at different slope positions(P<0.05), mainly concentrated in the middle slope and lower slope; soil ammonium nitrogen, soil nitrate nitrogen, soil available phosphorus and soil available potassium content mainly concentrated in the upper slope position and the lower slope position, while the p H was mainly concentrated in the middle of the slope. The soil urease activity and soil catalase activity showed a decreasing trend with the slope down and larger at upper and lower slope. The sucrase activity was mainly concentrated in the middle and lower slopes. The 14 soil indicators were divided into five common factor groups through factor analysis, namely soil fertility factor, soil water factor, soil structure factor, soil nutrient factor and soil biological factor. The characteristics of cultivated layer of sloping land were analyzed through soil quality index. It was found that the quality index of each soil layer after a year of no-tillage was higher at lower slope position than those at the upper and the middle slope positions. After two years of no-tillage, the soil quality index of the middle slope and the lower slope was higher than that of the upper slope. It was concluded that a soil condition with a relatively balanced and higher fertility quality was formed at the lower slope. After two years of notillage, the soil quality in the middle slope was improved compared with that before no-tillage.