Irrigation water supplies are dwindling in the southern High Plains and effective methods of conserving precipitation during fallow periods are needed. This study was conducted to compare soil water storage, yield of cotton, and profitability of conventional and notillage in a 2‐yr, double crop, irrigated barley (Hordeum vulgare L.)‐ dryland cotton (Gossypium hirsutum L.) cropping sequence with a 48 wk fallow from barley harvest and cotton planting. The soil was a Sherm (fine, mixed, mesic Torrertic Paleustolls) clay loam with 2.2% organic matter, a soil pH of 6.9, and 28, 31, and 41% sand, silt, and clay, respectively. Kochia [Kochia scoparia (L.) Schrad.], Russian thistle [Salsola kali (L.) var. tenuifolia Tausch], pigweed (Amaranthus blitoides S. Wats.), and witchgrass (Panicum capillare L.) were controlled during fallow with disk and field cultivator in conventional tillage. Herbicides used for no‐tillage were dicamba [3,6‐dichloro‐2‐methoxybenzoic acid], atrazine [6‐chloro‐N‐ethyl‐N′‐(l‐methylethyl)‐1,3,5‐triazine‐2,4‐diamine], fluometuron [N,N‐dimethyl‐N′‐[3‐(trifluoro‐methyl)phenyl] urea], and glyphosate [N‐(phosphonomethyl)glycine]. A 45 mm increase in soil water storage with no‐tillage increased dryland cotton yields 110 kg ha−1. Although herbicide costs were $155.00 ha−1 greater with no‐tillage, long‐term annual profit with no‐tillage increased $82.00 ha−1 over conventional tillage because of increased yield and lower machinery depreciation Costs.
