Effect of 1 m and 1.5 m row spacing on yield and fibre quality of upland cotton in Warren, NSW, Australia

Date Issued:2014-06-30

Abstract

Compaction caused by machinery traffic can have severe yield consequences. Compaction increases soil strength and reduces soil porosity, which hinders root growth, moisture and nutrient uptake, and plant growth. GPS-auto steer and modification of machines to 3 m wheel centres can minimise compaction of fields. Conventional 1 m cotton does not accommodate for 3 m wheel centres so row spacing can be altered to alleviate this issue. The aim of the experiment in this study was to test the hypothesis: is cotton yield and fibre quality in wide 1.5 m row the same as conventional 1 m rows? There were two main components to the experiment at Auscott Warren farm, a replicated plot experiment and a paddock scale whole block experiment. The replicated experiment was a RCB design with nine replicates of 1 m and 1.5 m row treatments. The paddock scale whole block was two large field blocks of 1 m and 1.5 m row treatments. 1.5 m cotton was 10 cm taller than 1 m cotton. There was little difference in harvest index (60%) between the two configurations. The 1 m cotton yielded 1.8 bales/ha and 3.6 bales/ha higher than the 1.5 m cotton in the machine picked and handpicked replicated experiment, respectively. Yield of 1 m cotton mainly came from fruiting nodes 1-8, position 1. In contrast, yield in 1.5 m cotton mainly came from vegetative fruiting branches. There was a strong positive correlation (R2 = 0.99) between the number of bolls/m2 and yield, but only a weak correlation between lint per boll and yield (R2 = 0.28), and between number of bolls and lint per boll (R2 = 0.21). Only minor differences in fibre quality were observed. Gross margins of the two row configurations were very similar. Future research should quantify water usage to improve grower decision making.

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