Cotton Growth and Production as Affected by Moisture, Nitrogen, and Plant Spacing on the Yuma Mesa

Acala 44 cotton was grown near Yuma, Ariz. on irrigated Superstition loamy sand having a steep productivity gradient from one end of the field to the other. Effects of soil moisture, N rate, and plant spacing, each at 3 levels in a factorial experiment, were determined for vegetative growth, fruiting, N uptake, yields, and ginning and fiber characteristics. Yields were increased substantially by N, and significantly, but less so by moisture and spacing. The spacing effect was limited to the second of 2 pickings. Considering the 4 direct factors which determine cotton yields (total flowers, percent boll‐set, boll size, and percent lint) fertilizer affected 2 and spacing 4 of these factors. The precision of the experiment did not permit a decision as to how moisture increased yields since none of the 4 factors were affected significantly. Cotton growth and production were unsatisfactory where substantial cuts were made in leveling the field before planting. The range of yields among individual plots varied almost 800% with a maximum of 2.51 bales and a mean of 1.28 bales of lint per acre. In spite of the large productivity gradient and resultant variations in growth and yield, relative response to a given treatment was remarkably consistent.