AN AGRONOMIC AND ECONOMIC COMPARISON OF THE WHEAT-CORN-FALLOW AND WHEAT-SORGHUM-FALLOW ROTATIONS

Winter wheat (Triticum aestivum L.) and grain sorghum [Sorghum bicolor (L.) Moench] in the central and southern Great Plains are often grown in a 3-yr wheat-sorghum-fallow (WSF) rotation. Corn (Zea mays L.) can be substituted for sorghum in northern areas but is believed to lack sufficient drought and heat tolerance far southwest Kansas and areas f urther south. However, interest in dryland corn is increasing. We cond ucted a study from 1992 through 1995 near Garden City, KS, to compare wheat-corn-fallow (WCF) and WSF. Four tillage systems were compared: a ll conventional tillage (CT); all reduced tillage (RT); all no-tillage (NT); and a CT wheat, NT corn or sorghum combination (CNT). Wheat yie lds were unaffected by rotation and tillage. Corn yielded more than so rghum in 12 of 16 tillage x year combinations, primarily due to above average precipitation. Corn yields were increased by RT and NT in 3 of 4 yr whereas they increased sorghum yields in only 1 yr. Average retu rns from WCF were $31.22/acre per yr, whereas those from WSF were $19. 79/acre per yr. Returns of WCF exceeded WSF returns in 10 of 16 tillag e x year combinations. Average income for CNT in WCF exceeded incomes from CT, RT, and NT by $6, $7.16, and $11.90/acre per yr, respectively . The CNT system in WSF produced $3.79/acre per yr more than RT and $6 .14/acre per yr more than NT, but $5.84/acre per yr less than CT. Unde r the conditions of this study, WCF was superior to WSF in terms of yi eld and return. The CNT system usually produced more return, particula rly in WCF.