286 Effects of Different Mulching and Tillage Systems on Soil Water Retention Under Drought Conditions in a Tomato Production System

Abstract

Water management is often the key to successful vegetable culture. Various mulching/tillage systems are often utilized in tomato production, depending upon the available resources of a particular grower, to achieve better water use efficiency. A study was conducted to compare six different mulching/tillage systems to observe the influence of these systems on soil water retention as well as on `Fabulous' tomato ( Lycopersicon esculentum Mill.) production. Winter ryegrass and wheat were the cover crops utilized and were mowed with the following six treatments then applied: 1) Conventional tillage (CT), 2) black plastic over conventional tillage (BP), 3) no-till with cover crop sprayed with Glyphosate prior to transplanting (NT-GLY), 4) strip-till with cover crop sprayed with Glyphosate prior to transplanting (ST-GLY), 5) no-till in which cover crop was mowed periodically during the growing season (NT), and 6) strip-till with cover crop mowed periodically during the growing season (ST). This test was conducted under severe drought conditions (45.4 mm of rain from 1 July to 30 Sept. 1999) with plants receiving no supplemental water via irrigation at any time throughout the study. Soil moisture was measured periodically throughout the growing season at a depth of 20 cm; soil and mulch surface temperatures were taken at similar timings as soil moisture. Soil moisture levels during the growing season indicated different patterns of water depletion when comparing the six treatments. There was no significant difference between the winter rye and wheat with respect to water depletion or tomato yields. Lower early tomato yields under NT, ST, NT-GLY, and ST-GLY indicate that cooler soil conditions, while aiding in the retention of soil moisture, delay early tomato production when compared to the warmer soil conditions found under CT and BP. Results also indicate that late season harvests under NT and ST systems produce predominantly cull fruits with a high incidence of blossom-end rot. The NT-GLY and ST-GLY systems tended to produce comparatively lower levels of cull fruit and blossom-end rot in late season harvests than any of the other six treatments.