Greenhouse soil properties and vegetable yield with dead pig and bamboo biochars

Abstract

A field experiment was conducted to determine the effect of dead pig (DPB) and bamboo (BB) bio-chars as well as their application patterns on yield and nitrogen (N) content in vegetables and on soil properties (pH, electrical conductivity, and N content) in an Ipomoea aquatica-Brassica chinensis rotation system at Banqiao Town, Lin'an City, Zhejiang Province, China. Treatments included (1) a control (no biochar); (2) one application of 20 t·hm-2 of 20-0-BB and (3) 20-0-DPB prior to the first I. aquatica crop; and two applications of biochars with 10 t·hm-2 being applied prior to the I. aquatica season and the remaining biochars[(4) 10-10-DPB or (5) 10-10-BB] being applied prior to the B. chinensis season at an application rate of 10 t·hm-2. The treatments were laid out based on randomized complete block design with four replications. The plant shoots of I. aquatica and Brassica chinensis in each plot were harvested after growth for 65 and 40 days, respectively. At each harvest time, five plants and five soil cores (0-200 mm) respectively from each plot were randomly collected and bulked for chemical analysis. Results showed that in the I. aquatica crop season, the 20-0-DPB treatment significantly increased (P < 0.05) the I. aquatica crop yield and soil pH. Also, the 20-0-DPB and 10-10-DPB treatments significantly increased (P < 0.05) yield of B. chinensis; whereas, the 20-0-BB and 10-10-BB treatments significantly decreased (P < 0.05) the I. aquatica crop yield. Additionally, the 20-0-DPB and 20-0-BB treatments significantly increased N (P < 0.05) in roots of I. aquatica Forsk but not in B. chinensis. The 10-10-DPB treatment significantly increased (P < 0.05) B. chinensis root N. Finally, biochar treatments had no significant effect on soil nitrate or vegetable shoot N. In conclusion, the dead pig biochar was more effective than the bamboo bio-char for increasing soil pH and vegetable yield with one application of dead pig biochar at 20 t·hm-2 appearing to be better than two split applications.