An agroclimatic probability study of the economics of fallow-seeded and continuous spring wheat in southern saskatchewan

Abstract

This analysis of the economics of spring wheat grown on fallow in a two-year rotation as compared with continuous wheat grown in the Brown soil zone of southern Saskatchewan includes three phases: 1. (1) the estimation of spring soil moisture by a meteorological soil water budgeting technique (versatile budget) and the verification of the estimates against observations over 20 years; 2. (2) the prediction of average and probable yields from fallow-seeded wheat fields in two-year rotation and from continuous wheat using published water use-yield relationships; and 3. (3) the evaluation of average and probable net returns from fallow-seeded wheat and continuous wheat using the estimated yields and published data on production costs. Spring soil moisture estimates were significantly correlated with the corresponding observations on fallow ( r = 0.78) as well as on stubble ( r = 0.73) lands. The observed and estimate means over 20 years did not differ significantly and the standard errors of estimate were about 1.2 inches. Estimated average wheat yields (bu/acre) from continuous wheat were 71% of yields from fallow-wheat. In three out of ten years net return from continuous wheat were less than those from fallow-seeded wheat. Based on an average farm wheat price of $1.65 per bushel, average (strictly medium = 50% probability) annual net returns per cultivated acre were $13.23 for continuous wheat seeded over the whole area and $9.53 for fallow wheat in a two-year rotation seeded over half of the area under cultivation. But probable net returns fluctuated more widely for continuous wheat than for fallow-seeded wheat. One inch of water beyond an initial six inches of available water yielded $2.53 in terms of additional net returns from fallow-seeded wheat and $5.05 from continuous wheat. The use of the proposed techniques for evaluating economic benefits in various soil and climatic zones by simulated changes in the crop rotation program is demonstrated.