Effects of vermicomposts on tomato yield and quality and soil fertility in greenhouse under different soil water regimes

• Under 60–70% of field capacity (θf), vermicompost (VM) had higher yield and Vc content.
• VM had higher available N and P contents in soil than the other treatments under 70–80%θf.
• VM increased the activities of acid phosphatase, catalase and urease in soil compared to the other treatments.

Vermicompost has great commercial potential in the horticultural industry and its effectiveness is affected by soil water regimes. The effects of vermicompost (VM) on tomato yield and quality and soil fertility were compared with chick compost (CM), horse compost (HM) and chemical fertilizer (CF) in a greenhouse under the three soil water regimes (50–60, 60–70 and 70–80%θf, θfis field capacity). Additionally a control treatment (CK, no fertilization) was included. Under 60–70%θf, VM increased the yield by 16.3, 9.6, 52.0 and 69.3%, and the vitamin C (VC) content by 8.2, 59.2, 15.2 and 80.3% when compared to CM, HM, CF and CK, respectively. However, VM decreased the soluble solids and total acidity under three soil water regimes. Total acidity in VM was 17.8, 4.8, 26.4 and 9.1% lower than that in CM, HM, CF and CK, respectively, and the sugar/acid ratio (the ratio of soluble solids to total acidity) in VM was also lower than the other two composts, but higher than CF and CK. VM had the highest sugar/acid ratio under 50–60%θf. The sugar/acid ratio in VM decreased with the increase of soil water content. VM had lower soil organic matter content than CM and HM, but higher than CF and CK under the three soil water regimes. The soil organic matter content in VM was 17.0 and 12.7% lower than that in CM and HM, but 12.9 and 10.1% higher than that in CF and CK. VM had higher available N and P contents in soil than the other treatments under 70–80%θf. VM increased the activities of acid phosphatase, catalase and urease in soil compared to the other treatments under the three soil water regimes. Thus vermicompost increased tomato yield and VC under 60–70% of field capacity and the effects of vermicompost on soil fertility varied with soil water regime.