Date of Award
Master of Science
Plant and Soil Science
Although most vegetables are grown using conventional tillage (CT) practices, no-tillage (NT) is becoming more prominent in vegetable production due to growers gaining more understanding of the economic and ecological benefits associated with the NT production system. Nitrogen (N) fertility management in NT systems is important to maximize yield productivity, but there is little available information on N fertilizer recommendations for vegetable crops grown in this production system. Therefore, two field studies were conducted at a grower location in southern Illinois to determine the effect of N application rates in NT zucchini squash and cucumber production following the herbicide burn-down of a wheat cover crop in early spring. Results indicated that the maximum total squash fruit yield was achieved when 30 to 120 lb N/acre was sidedress applied [or a range of 125 to 210 lb total N (pre-plant, soil, and applied N)/acre]. Although squash plant growth was maximized when 180 lb N/acre was sidedressed (or a range of 264 to 273 lb total N/acre), the overall yield was less compared to the 30 to 120 lb N/acre rates. Cucumber results indicated that maximum total fruit yield was achieved again at 30 to 120 lb N/acre sidedress rates (or a total N rate range of 114 to 208 lb/acre). Cucumber plant growth was maximized at a sidedress application of 120 to 180 lb N/acre, although yield decreased at the 180 lb N/acre sidedress rate (or 260 to 270 lb total N/acre). It appears that if cucurbit vegetables have high amounts of N available in the soil through over application of N fertilizer, the excess N will be used for plant vegetative growth rather than for fruit production. These studies indicated that when too much N is applied in both NT cucumbers and zucchini squash, these high N rates will stimulate vegetative growth (as indicated by high plant vigor and leaf chlorophyll content) while reducing fruit yields.
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