套作及秸秆还田对西兰花连作田土壤团聚体分布的影响

随着蔬菜的规模化与集约化发展,菜田连作障碍日趋严重,合理间套作与秸秆还田对恢复菜田土壤生态环境有很大的潜力。该文基于6a的田间长期定位试验,以西兰花单作为对照,设置西兰花套作糯玉米且糯玉米秸秆还田-西兰花(B/MR-B)、西兰花套作糯玉米且糯玉米秸秆不还田-西兰花(B/M-B)、西兰花-西兰花(B-B),共3个处理。采用湿筛法探索了套作糯玉米(Zea mays L.sinensis Kulesh)并秸秆还田对连作西兰花(Broccoli)田土壤固碳能力以及土壤水稳定性团聚体分布的影响。结果表明:随着土层的增加,不同处理的水稳定团聚体分布呈粒径逐渐减小、分布范围呈逐渐集中趋势。随着生育时期的推进,幼苗期和花球生长期水稳性团聚体多集中于0.25~0.5 mm与0.25 mm粒径范围;营养生长期多集中于0.5~1 mm与0.25~0.5 mm粒径范围;而秋菜收获期则多分布于0.5~1 mm、0.25~0.5 mm与0.25 mm粒径范围。B-B处理下各个时期0~40 cm土层的粒径0.5~1 mm和0.25~0.5 mm的水稳性团聚体基本呈现低于其他处理,相反B-B处理下的粒径0.25 mm水稳性团聚体均呈现显著高于其他处理。秋季西兰花整个生育期水稳定性大团聚体均表现为B/MR-BB/M-BB-B。B/MR-B处理的土壤有机碳(SOC)含量显著高于其他处理。多元回归分析表明土壤水稳定性大团聚体与土壤有机碳含量在0~10 cm与10~20 cm土层中呈极显著(P0.01)正相关,20~40 cm土层呈显著(P0.05)正相关。综上,套作糯玉米并秸秆还田能有效提高连作西兰花田耕作层土壤水稳定性大团聚体的比例,改善连作导致的土壤理化性状的恶化。

Effects of intercropping and waxy maize stalk returning on distribution of soil aggregate and soil organic carbon in broccoli continuous cropping filed

With the large-scale and intensive development of vegetable planting, continuous cropping obstacles have become more and more serious. Intercropping farming and straw returning have great values for improving soil ecological environment in vegetable fields. The objective of this study was to evaluate the changes of soil water-stable aggregate distribution and stability after 6 years in response to long-term relay-intercropping and crop straw management experiment in broccoli and waxy maize cropping system. Three treatments were used: relay-intercropping mode of broccoli and waxy maize with waxy maize straw returning (B/MR-B), relay-intercropping mode of broccoli and waxy maize without waxy maize straw returning (B/M-B) and broccoli continuous cropping (B-B). As a result, the size class of soil water-stable aggregate decreased with the soil layers deepening, while the distribution range was concentrated. The main ranges in seedlingperiod and ball-flower growth period were 0.25—0.5 mm and <0.25 mm size classes. In vegetative period, the main ranges were 0.5—1 mm and 0.25—0.5 mm size classes. While in vegetable harvest period, the main ranges were 0.5—1 mm, 0.25—0.5 mm and <0.25 mm size classes. The size classes of 0.5—1 mm and 0.25—0.5 mm in B-B treatment were lower than in other treatments. On the contrary, the size classes of <0.25 mm in B-B treatment were significantly higher than in other treatments. During whole growth period of broccoli, the water-stable macro-aggregate followed by B/MR-B>B/M-B>B-B. Relay-intercropping with straw returning significantly increased the content of the soil organic carbon (SOC). Meanwhile,the water-stable macro-aggregate was also correlated with the SOC content according to the multiple regression analysis. The water-stable macro-aggregate was extremely significantly positively correlations with SOC in the 0—10 cm and 10—20 cm layers (P<0.01). In the 20—40 cm layers, the water-stable macro-aggregate were significantly positively correlations with SOC (P<0.05). Our findings indicated that relay-intercropping with straw returning increases the proportion of water-stability aggregate, improves soil physical and chemical properties and reduces continuous cropping obstacles.