Planting geometry and growing season effects on the growth and yield of dryland cotton

Authors: Baumhardt, Roland - Louis; Schwartz, Robert; Marek, Gary; BELL, JOURDAN - Texas Agrilife Extension

Submitted to: Agricultural Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/22/2018
Publication Date: 1/25/2018
Citation: Baumhardt, R.L., Schwartz, R.C., Marek, G.W., Bell, J.M. 2018. Planting geometry and growing season effects on the growth and yield of dryland cotton. Agricultural Sciences. 9(1):99-116. https://doi.org/10.4236/as.2018.91008.
DOI: https://doi.org/10.4236/as.2018.91008

Interpretive Summary: Dryland farming may replace irrigation as water from the declining Ogallala Aquifer becomes scarce. Cotton is a good dryland crop if new farm practices can offset the yield limiting growing season energy in the southern High Plains. Scientists from ARS in Bushland, Texas and Texas A&M AgriLife Research and Extension Service tested row and plant spacing effects on cotton fiber quality and yield using field plots and crop simulation. Cotton grown in narrow, 25 to 50 cm row widths and 7.5 to 10 cm frequency were shorter and had fewer bolls per plant than with common 76 cm rows. Increased populations with narrower row and plant spacing did not increase yield. Early bolls did not improve fiber. Computer simulated cotton growth for 42 seasons also had shorter plants with fewer bolls in the narrow row and plant spacing treatments. These results show farmers and crop consultants that dryland cotton planted with narrow row and plant spacing was not earlier and yielded the same or less lint.

Technical Abstract: The declining Ogallala Aquifer beneath the Southern High Plains may necessitate dryland crop production and cotton (Gossypium hirsutum L.) is a well-adapted and potentially profitable alternative crop. The limited growing season duration of the Texas Panhandle and southwestern Kansas, however, imposes significant production risk due to incomplete boll maturation. Emphasizing earlier boll production that is usually confined to sites on lower fruiting branches may reduce risk, but offsetting high planting densities are needed to maintain desirable lint yield. Our objectives were to quantify planting (i) row width and (ii) in-row spacing effects on growth, yield, and fiber quality of dryland cotton. Field tests of row widths from 0.25 to 0.76 -m and plant densities with in-row spacing ranging from 0.075 to 0.15 -m were conducted from 1999 to 2006 on a nearly level Pullman clay loam (fine, mixed, superactive, thermic Torrertic Paleustoll) managed in a wheat (Triticum aestivum L.), cotton, fallow (W-Ctn-F) rotation. To expand the basis of comparison, cotton growth and yields were simulated using GOSSYM and long-term (1958-2000) weather records from Bushland, TX, as input for all combinations of 0.38 or 0.76 – m row widths and plant spacing of 0.075, 0.10 and 0.15 – m. Experimental and computer simulated plant height and harvested boll number increased significantly with increased row spacing and, occasionally, in-row plant spacing. Modeled lint yield for 0.38 m rows decreased by approximately 50% compared with the 582 kg/ha yield for conventional row spacing, which was practically duplicated by field observations in 2001 and 2004. Measured fiber quality occasionally improved with conventional row spacing over ultra-narrow rows, but was unaffected by plant spacing. Because narrow rows and frequent plant spacing did not improve lint yield or fiber quality of dryland cotton, we do not recommend this strategy to overcome a thermally limited growing season.