Cotton often requires supplemental nitrogen (N) fertilization to achieve maximum lint yields. Proper N rates are critical as lower rates may limit yields while higher rates promote excessive vegetative growth, delay harvest, and reduces fiber quality.The increasing cost of nitrogen fertilizers has given producers additional incentives to closely manage N inputs. Higher than optimal N rates may also contribute to increased disease and insect pressure. Peak demand for N by cotton plants begins at pin-head square (PHS) and continues through boll fill. Nitrogen management of cotton is complicated as N may be lost by leaching, volatilization, and denitrification. Split applications allow producers to better manage these risks. Midseason management of Nfertility is dependent on obtaining reliable and timely data about the field/plant nitrogen status. Several methods are available to cotton producers to determine plant/field N status. These methods include petiole analysis NO3, total N % of leaf blades, soil testing for NO3 & NH4, and determination of plant greenness using a chlorophyll meter. Little is known about how these methods compare in their ability to predict yield response in irrigated cotton grown in SE Missouri.
展开▼
