COTTON CROP ENVIRONMENT GROWTH AND YIELD IN SUDAN GEZIRA .I. GEZIRA OBSERVATION PLOTS - EXPERIMENTAL DESIGN CULTURAL METHODS AND YIELD ANALYSIS

Analysis of 21 years’ cotton yield data from factorial experiments at three sites in the Sudan Gezira established that yields were significantly increased by nitrogenous fertilizer, that close spacing outyielded wide spacing and that variety X1730A (L type) outyielded variety MSDS (a Sakel type). The effect of nitrogen varied depending on variety and spacing and there were also marked variations from year to year in the effects of nitrogen, spacing, variety and some of the interactions. Year-to-year variations in the overall level of yield were very pronounced and accounted for more than half of the total variance at each site. Causes of year to year variation and the mechanism of the treatmenteffects will be discussed in subsequent papers. © 1969, Cambridge University Press. All rights reserved.