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ARS Home » Research » Publications at this Location » Publication #81680
Title: NITROGEN REQUIREMENTS OF BROCCOLI IN COVER CROP MULCHES AND CLEAN CULTIVATION

Author
item ABDUL BAKI, AREF
item MORSE, RONALD - VPI AND STATE UNIVERSITY
item TEASDALE, JOHN
item Devine, Thomas

Submitted to: Journal of Vegetable Crop Production
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/21/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary: In the mid-Atlantic states, broccoli can only be grown from seedlings as a fall crop. The conventional method is to use clean cultivation -- a system that requires a lot of plowing and herbicides to control weeds. This system causes soil erosion and washing of nutrients by run-off water. We developed a no-tillage, environmentally friendly system for growing broccoli. It uses forage soybean as a summer cover crop. At broccoli transplanting time, the soybean cover crop is mowed and left on the soil surface as a mulch. The The broccoli transplants are planted into it without tillage or cultivation. The soybean mulch provides part of the nitrogen required by the broccoli crop, releases other nutrients, protects soil from erosion, adds organic matter to the soil, and inhibits weed growth. Yields under the no-tillage soybean mulch system are higher than those in the conventional system and production cost is lower due to savings on cultivation, herbicides, and nitrogen. This research benefits growers and farmers.

Technical Abstract: 'Emperor' broccoli was grown in the fall of 1996 at the Beltsville Agricultural Research Center (BARC), MD, and at the Kentland Agricultural Research Farm (KARF), Virginia Polytechnic Institute and State University, Blacksburg, VA. The objective was to determine the N requirements of broccoli grown in a no-till production system in which mulches from cover crops provide part of the N. The mulch treatments included cover crops of forage soybean, foxtail millet and a combination of soybean and millet, as compared to the conventional clean cultivation production system. Supplemental N, as ammonium nitrate from commercial fertilizer, was applied to all mulch treatments at 0, 112, and 224 kg.ha-1. Cover crop biomass ranged from 3.6 to 5.2 t.ha-1 with N content of 10 kg.t-1 for millet to 28 kg.t-1 for soybean. The cover crops provided only part of the N required by the broccoli crop. Yield and head mass increased with additional N application from commercial fertilizer up to 224 kg.ha-1. Estimated N distribution in the plant among the head, leaves, stem, and roots was 22, 58, 6, and 14%, respectively. The mulch provided part of the N requirement, increased organic matter and prevented soil erosion.