Fresh market tomato yield and soil nitrogen as affected by tillage, cover cropping, and nitrogen fertilization

Sustainable practices are needed in vegetable production to maintain yield and to reduce the potential for soil erosion and N leaching. We examined th e effects of tillage [no-till (NT), chisel plowing (CP), and moldboard plow ing (MP)], cover cropping [hairy vetch (Vicia villosa Both) vs. winter weed s], N fertilization (0, 90, and 180 kg.ha(-1) N), and date of sampling on t omato (Lycopersicon esculentum Mill.) yield, N uptake, and soil inorganic N in a Norfolk sandy loam in Fort Valley, Ga. for 2 years. Yield was greater with CP and MP than with NT in 1996 and was greater with 90 and 180 than w ith 0 kg.ha(-1) N in 1996 and 1997. Similarly, aboveground tomato biomass ( dry weight of stems + leaves + fruits) and N uptake were greater with CP an d MP than with NT from 40 to 118 days after transplanting (DAT) in 1996; gr eater with hairy vetch than with winter weeds at 82 DAT in 1997; and greate r with 90 or 180 than with 0 kg.ha(-1) N at 97 DAT in 1996 and at 82 DAT in 1997. Soil inorganic N was greater with NT or CP than with MP at 0- to 10- cm depth at 0 and 30 DAT in 1996; greater with hairy vetch than with winter weeds at 0- to 10-cm and at 10- to 30-cm at 0 DAT in 1996 and 1997, respec tively; and greater with 90 or 180 than with 0 kg.ha(-1) N from 30 to 116 D AT in 1996 and 1997. Levels of soil inorganic N and tomato N uptake indicat ed that N release from cover crop residues was synchronized with N need by tomato, and that N fertilization should be done within 8 weeks of transplan ting. Similar tomato yield, biomass, and N uptake with CP vs. MP and with 9 0 vs. 180 kg.ha(-1) N suggests that minimum tillage, such as CP, and 90 kg. ha(-1) N can better sustain tomato yield and reduce potentials for soil ero sion and N leaching than can conventional tillage, such as MP, and 180 kg.h a(-1) N, respectively. Because of increased vegetative cover in the winter, followed by increased mulch and soil N in the summer, hairy vetch can redu ce the potential for soil erosion and the amount of N fertilization require d for tomato better than can winter weeds.