不同耕作措施对红壤坡耕地耕层质量的影响

为探明不同耕作措施对云南红壤坡耕地耕层土壤抗侵蚀性能和生产性能的影响,以常规耕作为对照,设置免耕、翻耕20 cm、翻耕20 cm+压实、翻耕20 cm+深松30 cm四种耕作措施,采用土壤质量指数法对不同耕作措施下耕层质量变化特征进行分析评价。结果表明:(1)不同耕作措施对红壤坡耕地耕层土壤抗侵蚀性能影响显著。翻耕20 cm+深松30 cm处理下土壤饱和导水率最大(1.19mm·min^-1);与常规耕作相比,翻耕20 cm+深松30 cm处理下水稳性团聚体平均质量直径增加28.13%;免耕处理下土壤抗剪强度最高(12.12kg·cm^-2),耕层土壤饱和导水率最大(1.27mm·min^-1);翻耕20 cm处理下大于0.25 mm水稳性团聚体含量、水稳性团聚体平均质量直径、几何平均直径均显著高于其他措施,分别为69.64 g·kg^-1、1.74 mm、0.77 mm。(2)不同耕作措施对红壤坡耕地耕层生产性能影响具有差异性表现,免耕处理下土壤容重显著增大,土壤有机质、有效磷在表层富集;翻耕20 cm、翻耕20 cm+深松30 cm处理下,耕层增厚效果显著,土壤有机质、有效磷含量显著增加。(3)红壤坡耕地耕层土壤质量及诊断指标的适宜性对耕作措施响应有差异,翻耕20 cm+深松30 cm处理耕层土壤质量指数最大(0.58);翻耕20 cm、翻耕20 cm+深松30 cm处理的耕层厚度、容重及有效磷指标均在适宜性阈值范围。上述研究结论可为红壤坡耕地适宜耕作措施选择以及坡耕地合理耕层的构建与评价提供参考。

Effects of Tillage Measures on Quality of Cultivated-layer in Red Soil Slope Farmland

【Objective】Red soil slope farmlands are an important cultivated land resource in South China.Because of long-term unreasonable tillage measures and uneven spatial and temporal distribution of precipitation,resultant serious soil erosion on slope farmlands in this area has led to a sharply declining productivity and low and unstable crop yields,thus seriously restricting development of the agriculture in South China.Reasonable tillage measures play an important role in improving soil structure,increasing water use efficiency,preventing soil erosion,improving ecological environment,building up land productivity and raising crop yields.In this paper,a tract of red soil slope farmland in Yunnan Province was taken as research object.Farmlands under different tillage measures were compared in soil quality.This study was conducted to explore mechanisms of tillage measures affecting erosion resistance and production performance of the cultivated-layers of the farmlands,in an attempt to provide certain scientific basis for quality evaluation of the cultivated-layers of red soil slope farmlands and improvement of conservative tillage technologies for red soil slope farmlands.【Method】In this study a total of 15 experimental plots were set up and cultivated for comparison between different tillage measures or treatments,i.e.CK(traditional tillage),NT(no-tillage),P20(tillage 20 cm in depth),P20C(tillage 20 cm in depth+compaction),and P20S30(tillage 20 cm+subsoiling 30 cm in depth),in soil quality of the cultivated layer,and one-way ANOVA and soil quality index method were used to analyze the experimental data.【Result】Results show:(1)The impacts of tillages on erosion resistare of the cultivated-layers in red soil slope farmlands.Compared with Treatment CK,Treatment P20S30 increased by 28.13%in average mass diameter of water-stable aggregates.Treatment NT was the highest in shear strength(12.12 kg·cm^-2),and in soil saturated hydraulic conductivity(1.27 mm·min^-1)as well.Treatment P20 was the highest in content of>0.25 mm water-stable aggregates,in mean weight diameter of water-stable aggregates and in geometric mean diameter of the aggregates,reaching up to 69.64%,1.74 mm and 0.77 mm,respectively;(2)The impact of tillage on productivity of the cultivated-layer in red soil sloping farmland varied with treatment.In Treatment NT,soil bulk density significantly increased,and soil organic matter and available phosphorus concentrated in the surface layer.In Treatment P20 and P20S30,the cultivated-layer was significantly thicker,and the soil organic matter and available phosphorus contents increased significantly;(3)And the effect of tillage on soil quality of the cultivated-layer and on the suitability of the diagnostic indices varied with treatment.Treatment P20S30 was the highest in soil quality index(0.58);and Treatments P20 and P20S30 varied within the range of suitability in thickness,bulk density and available phosphorus index of the cultivated-layer.Treatment P20 was the highest in organic matter content.【Conclusion】All the findings in this study may serve as reference for selection of suitable tillage measures,and evaluation and construction of a rational cultivated-layer in red soil slope farmlands.