水旱轮作条件下免耕土壤主要理化特性研究

Study on Main Physicochemical Properties in No-tillage Soil under Paddy-Upland Rotation

采用野外调查取样与室内分析相结合的方法,研究了水旱轮作条件下,不同免耕年限土壤主要理化特性的变化特点。结果表明：（1）水作及旱作后,随免耕年限延长土壤容重在免耕7-8年达到最大值,与常规耕作差异显著,长期免耕导致土壤板结;土壤pH值在免耕2-3年显著低于常规耕作,免耕致使土壤酸化。（2）水作及旱作后,免耕土壤有机质、全氮、速效氮、速效磷、速效钾均在表层（0-5 cm）富集。（3）水作及旱作后,免耕土壤耕层有机质、全氮均高于常规耕作,随免耕年限延长,免耕7-8年时明显下降;旱作后耕层土壤速效氮、速效磷变化特征与有机质和全氮一致,水作后免耕土壤速效氮含量高于常规耕作,但各免耕年限间无显著差异,土壤速效磷在免耕5-6年达到最大值,显著高于常规耕作,后随免耕年限延长变化趋于稳定;水作及旱作后,土壤速效钾在免耕5-6年内,与常规耕作均无显著差异,免耕7-8年达到最大值。水作与旱作相比,各肥力指标均表现为水作高于旱作。

The research studied the changes of the physicochemical properties in soil of different no-tillage years under the paddy-upland rotation through investigation and laboratory analysis. The results showed that. （1） After paddy cropping and upland cropping, the maximum of soil bulk occurred in the year of 7-8, along with the no-tillage years increasing. It was significant difference compared with that in the conventional soil. Long-term no-tillage can make the soil compact. Soil pH value was significantly higher than that of conventional tillage at the year of no-tillage 2--3. No-tillage can make the soil acidizing. （2） The surface （0--5 cm） gathering phenomenon of organic matter, total nitrogen, available nitrogen, available phosphorus, and available potassium was obvious in the no-tillage soil. （3） After paddy cropping and upland cropping, the contents of organic matter and total nitrogen in the plough layer were higher than that of conventional tillage and decreased significantly in no-tillage 7-8 years, along with the no-tillage years increasing, After upland cropping, the tendency of available nitrogen and available phosphorus were consistent with organic matter and total nitrogen. After paddy cropping, the content of available nitrogen in no-tillage was higher than that of conventional soil, but there was no significant difference among different no-tillage years. Available phosphorus kept stabilization after no-tillage 5-6 years when the content of it reached a maximum, and was significantly higher than that of conventional tillage. After paddy cropping and upland cropping, the content of available potassium has no significant difference compared with conventional tillage in no-tillage 5-6 year and the highest content occurred in the year of 7-8. The contents of fertility index were higher in the condition of paddy cropping compared with upland cropping.