Studies on the Damage to Upland Crops Caused by Weeds

III. Competition between Crops and Weeds on Absorption of Nitrogen

Abstract

In this paper the competition between crops and weeds on absorption of nitrogen was reported.
1) Nitrogen content (%) per dry matter weights decreased with the growing process of crops. It was the least in corn, medium in upland rice, and the largest in soybean and peanut.
2) Effect of weeding on seasonal change of nitrogen content (%) was largely under wide spacing in upland rice and corn, only a little on both spacing in soybean and peanut.
3) Competition between crops and weeds on nitrogen absorption was appeared seriously at early stage in corn, and nitrogen content was decreased earliar than weight of dry matter. In legminous crops its competition was not serious, but in upland rice it was serious at middle stage of growth.
4) Nitrogen content (%) in each kind of weed was differed a little on each croping fields.