Effects of biological tillage on physicochemical properties and soil enzyme activity and growth and quality of Brassica oleracea var. italica

Field plot experiments were conducted to investigate the effect of biological tillage (inoculating earthworm) on soil physicochemical properties, enzyme activity and growth and quality of Brassica oleracea var. italica. Three treatments conventional tillage (CK), no tillage (T1) and biological tillage (T2) were set up for the experiment. The results showed that biological tillage increased soil nutrient content and soil moisture compared with CK, especially in the 5~20 cm soil layer. Also compared with CK, the contents of soil organic matter, total nitrogen, available phosphorous, and moisture under biological tillage treatment improved by 58.33%, 68.93%, 67.06% and 16.19%, respectively. Similarly, enzyme activities of soil catalase, urease and saccharase under biological tillage were significantly different from those under CK (P < 0.05). Plant height, leaf extent, leaf length and leaf width of B. oleracea were also significantly different from those of CK (P < 0.05). There was no significant difference in chlorophyll content among the three treatments. Biological tillage enhanced net photosynthetic rate of B. oleracea. The quality of B. oleracea advanced greatly, Vc content under T2 was 1.2 times that of CK. Gluconsinolates content of B. oleracea was as well higher than that of T1 and CK by 1.05 mol·g^-1 and 3.29 mol·g^-1 (P < 0.05), respectively. No significant difference was noted in soluble sugar content among the treatments. Increased earthworm (biological tillage) activity was contributed to improved soil physicochemical properties and enzyme activities in agro-ecosystems, which was critical for improving soil fertilization.