Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: January 30, 2000
Publication Date: N/A
Interpretive Summary: In the Southwest USA, the change from conventional to conservation tillage has been estimated to save soil losses of 1.2 t/ac/yr. In production areas where supra-optimal temperatures are prevalent, such as in south Texas, yields from reduced tilled cotton have often been the same or greater than yields of conventionally-grown cotton. Our 1999 objectives were to document both edaphic and abiotic conditions within commercial conventiona (CVT) and no-tilled (NT) cotton fields in order to better understand their relationships to plant water status and yield. Six farmer cooperators established both CVT and NT cotton in companion commercial fields in south Texas. Irrigation was used by one-half of the cooperators. Irrigation was beneficial to plant, soil, and air cooling and yield, however, NT soil (to 8") was also cooler and their leaves showed less stress, resulting in slightly higher lint yields than did the CVT-grown cotton. Additional benefits of conservation tillage include improved soil structure, increase soil biota and arthropods, cooler soil and decreased preplant soil moisture loss.
Technical Abstract: Research was carried out at the farm level to assess edaphic, abiotic, leaf blade nutrient and color, and plant water status differences between conventionally tilled (CVT) and reduced-tilled (NT) cotton. In 1999, six farmer cooperators established both CVT and NT cotton in companion commercial fields in south Texas. Irrigation was used by one-half of the cooperators. Three subsampling areas within each tillage system (sub-plot were established for access tube placement and sampling measurements. Continuous soil and air temperatures were recorded in each sub-plot between 7 June and 11 July. Results indicated that irrigated fields had lower plant canopy and soil temperatures at 5, 10 and 20 cm depths, higher soil moisture, lower water stressed leaf blades, lighter (less green) leaves, and higher N, P, Ca, and Zn leaf blade nutrient levels than did dryland cotton. No tillage fields had similar plant canopy temperatures, but cooler soil temperatures to 20 cm and, at the time of sampling, less soil moisture at 25 and 50 cm depths (dryland, only) compared to CVT fields. Leaf blade diffusive resistance and Zn levels (irrigated only) were lower in NT leaf blades than in CVT leaf blades. Lint yields were improved by NT (P<0.24) as was percent lint (P<0.07), compared to CVT fields. Plant stand was higher in NT fields supplied with irrigation.