不同年限蓖麻连作对土壤团粒结构的影响

本文通过研究不同年限蓖麻连作对土壤团聚体组成及其影响因素的分析，以期对蓖麻连作土壤结构性退化和连作障碍提供理论依据。通过采样及土壤机械干筛法将不同连作年限这4种处理进行土壤粒径分组，得到大团聚体、中间团聚体、微团聚体及粉黏粒组分质量，测定各组分团聚体的每100克结构百分比，分析土壤团聚体的年际动态分布及规律。中间团聚体随着连作年份的累加呈现出先上升再下降的的趋势，连作5年、10年蓖麻田分别较CK提高13.27%、0.36%；土壤容重随着蓖麻种植年限的增加呈现出先下降再上升再下降的变化趋势，且连作5年、10年、20年较对照降低了11.51%、6.47%、12.23%，土壤含水量较CK分别提高2.61%、10.10%、1.30%。短期连作较轮作蓖麻田而言并未对土壤造成结构性退化，但连作10-20年的蓖麻田的微团聚体和粉黏粒高于对照，造成土壤结构的退化，不利土壤团聚体的稳定性和良好结构。

Effects of continuous cropping of castor-oil plant in different years on soil aggregate structure

This paper studies castor fields with different continuous cropping years ,analyzes the structural degradation of castor continuous cropping soil, in order to provide a theoretical basis for physical indicators.Through simultaneous sampling and soil mechanical dry sieving method, we group the four treatments with different continuous cropping years into soil particle size, and then measure the mass of large aggregates, intermediate aggregates, micro aggregates and powder clay particles, and determine the structural percentage of each component aggregate per 100 grams. Finally analyze the interannual dynamic distribution and law of soil aggregates.We found that the intermediate agglomerates showed a trend of first rising and then falling with the accumulation of continuous cropping years. Compared with CK, the castor field for 5 years and 10 years of continuous cropping increased by 13.27% and 0.36% respectively. With the increase of castor planting years, the soil bulk density shows a trend of first decreasing, then increasing and then decreasing. Compared with the control, the continuous cropping for 5 years, 10 years, and 20 years reduced by 11.51%, 6.47%, and 12.23%, and the soil water content was increased by 2.61%, 10.10%, and 1.30% respectively.Short-term continuous cropping did not cause structural degradation to the soil compared to castor rotation cropping. However, the micro-aggregates and powder clay of castor-oil plant for 10-20 years were higher than the control, resulting in degraded soil structure, and not conducive to stability and good soil aggregate structure.