分层旋耕对水稻土耕层物理性状的影响

Effect of stratified rotary tillage on paddy soil physical properties

[目的]稻麦轮作制因稻季土壤淹水沉实及长期浅耕等因素导致耕层浅薄、土壤硬化,成为阻碍旱季作物生长的主导因素,拟论证使用分层旋耕（stratified rotary tillage,SRT）实现水稻土深松的技术可行性.[方法]构建原位分层旋耕试验台,通过对比分析免耕（no tillage,NT）、常规旋耕（conventional rotary tillage,CRT）与分层旋耕3种耕作方式的稻茬麦各生理期的土壤持水量、密度、含水率、土壤硬度等的连续变化情况,论证分层旋耕对水旱轮作制旱作季土壤物理性状的影响.[结果]分层旋耕可显著改善土壤物理性状.SRT与NT和CRT相比,可有效增加土壤疏松层深度、提高土壤持水量、降低土壤密度与贯入阻力.SRT处理后10-20 cm土层的平均持水量分别比NT、CRT高3.6%和3.5%,平均密度分别比NT、CRT低0.14和0.13 t·m^-3,麦季各时期土壤含水率明显提高,分别比CRT、NT高0.34%和1.21%.SRT明显降低0-30 cm的平均贯入阻力,其从大到小顺序依次为SRT、CRT和NT;SRT比CRT增加耕层厚度10 cm.[结论]分层旋耕耕作是解决水旱轮作区土壤硬化的适宜耕作技术,分层旋耕有利于改善稻茬田的土壤物理性状,从而利于促进旱季作物的生长.

[Objectives]Soil hardsetting in paddy season and long-term shallow tillage are two main constraints for low grain yield of wheat in rice-wheat rotation. There is a need to investigate whether stratified rotary tillage is a suitable solution and how stratified rotary tillage can affect paddy soil physics. [Methods]Three tillage systems,i.e.no till（NT）,conventional rotary till（CRT）and stratified rotary till（SRT）were conducted after paddy season to evaluate its effect on soil water holding capacity,soil porosity,water content and soil hardness during the ensuing wheat season. [Results]Stratified rotary tillage is a technically feasible tillage system for compacted paddy soils properties. Compared with NT and CRT,SRT significantly increased loosened soil layer depth,improved soil water holding capacity,reduced soil penetration while improved soil porosity. Water holding capacity in the 10-20 cm soil layer increased 3.6% and 3.5% as compared with NT and CRT,respectively. The mean soil bulk density decreased 0.14 and 0.13 t·m^-3,respectively. SRT greatly improved soil water content,whose value was 0.24% and 1.21% higher than the CRT and NT,respectively. In 0-30 cm soil layer penetration resistance was sequenced as SRT,CRT,NT. SRT improved 10 cm more loosened soil layer than traditional treatment. [Conclusions]Rehabilitating paddy soil structure requires stratified rotary tillage systems. Stratified rotary tillage is an effective means to improve paddy soil physics properties and thus is beneficial for post-paddy wheat production.