Soil management for irrigated vegetable production. I. The growth of processing tomatoes following soil preparation by cultivation, zero-tillage and an in situ-grown mulch

Abstract

A sequence of lettuce and tomato crops was grown in a field experiment on a sandy loam soil in order to study the relationship between soil tillage and plant growth under the near optimal water and nutrient conditions which are characteristic of vegetable production. This paper describes the performance of processing tomato crops, grown over two seasons under a range of soil management systems. The soil management systems included a cultivated and a zero-tillage treatment, as well as a zero-tillage treatment which followed a crop of subterranean clover (Trifoliurn subterraneum L.). The subterranean clover was sown in autumn and senesced in early summer to form an in-situ mulch. The bulk density of the soil in the zero-tillage treatment was high, and this was associated with a large reduction in vegetative growth, compared with the cultivated treatment. The bulk density of the soil was also high in the treatment where the subterranean clover was grown, but the vegetative growth of tomatoes was equal to that in the cultivated treatment. Despite the large differences in vegetative growth among treatments, there was no significant difference in the fruit yield. These results show that processing tomatoes can be successfully grown under zero-tillage when irrigation and fertilizer are well managed, and that vegetative growth and fruit yield are poorly correlated. The in-situ mulch of subterranean clover improved the physical conditions of the soil compared to the zero-tillage treatment, successfully controlled weeds and reduced soil erosion, but at the cost of having land out of production during the winter.