Submitted to: Agricultural Water Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 25, 2012
Publication Date: August 9, 2012
Citation: Anapalli, S., Nielsen, D.C., Ahuja, L.R., Ma, L., Lyon, D.J. 2012. Simulated yield and profitability of five potential crops for intensifying the dryland wheat-fallow production system. Agricultural Water Management. 116(2013):175-192. Interpretive Summary: Precipitation and stored soil water can be used more efficiently in dryland cropping systems if frequency of fallow is decreased. This can be accomplished by growing a spring- or summer-planted crop in the year following wheat harvest followed by a fallow period prior to the next wheat planting (i.e., producing two crops in three years rather than one crop in two years as is done with a wheat-fallow system). Several crops that could be inserted into the period between wheat harvest and the fallow period are corn, canola, and proso millet for grain and foxtail millet and triticale for forage. Cropping systems models can be used to generate simulated crop yields in order to evaluate the productivity and potential income of these crops to give farmers data to assess expected yield variability and production risk in producing these crops under dryland conditions in the central Great Plains. The Root Zone Water Quality Model (RZWQM2) was used to simulate yields of three grain crops and two forage crops at Akron, CO and Sidney Ne using weather data from 1948 to 2008 under seven initial soil water conditions. All five crops showed significant yield increases in response to increasing available soil water at planting. Calculated net returns were greatest for the two forage crops than for the grain crops. Proso millet was slightly more profitable than corn at Akron, while corn was the least profitable crop at Sidney. The distributions of simulated yields and net returns for the five crops provide valuable information for farmers to use in assessing yield variability and risk when contemplating intensification of their cropping system, and will help to guide crop selection when a measure or estimate of soil water at planting is available.
Technical Abstract: Greater precipitation use efficiency (PUE) and economic returns by increasing cropping frequency through the addition of summer crops to the dryland winter wheat- fallow (WF) cropping system have been reported in the semiarid Central Great Plains of USA. However, due to the highly variable nature of precipitation and uncertain water availability, selection of a crop with assured positive net returns to add to the system to increase cropping frequency is a challenge in the absence of reliable seasonal precipitation forecasts. The objective of this study was to evaluate long-term yields and net returns of several potential summer crops at various soil water contents at planting to assess their potential use in increasing dryland cropping frequency. Three grain crops [corn (Zea mays L.), canola (Brassica napus), and proso millet (Panicum miliaceum L.)] and two forage crops [foxtail millet (Setaria italica L. Beauv.) and spring triticale (X Triticosecale rimpaui Wittm.)] for which the Root Zone Water Quality Model (RZWQM2) had been calibrated at Akron, CO and/or Sidney, NE, were selected for investigation through modeling. The calibrated model was used to simulate yield responses of the crops to 25, 50, 75 and 100% of plant available water (PAW) in the soil profile at planting using recorded weather data from Akron, CO and Sidney, NE (1948-2008). Average costs of production and 10-yr average commodity prices for northeast Colorado were used to calculate net returns for each of the crops at the varying PAW levels. All crops showed significant (p<0.05) simulated yield increases in response to increasing initial PAW levels when those changes occurred in the entire 0-180 cm soil profile. The two forage crops gave greater net returns than the three grain crops for all initial PAW levels when calculated with 10-yr average prices received. Among the grain crops, proso millet was slightly more profitable than corn at Akron, while corn was the least profitable crop at Sidney. Using current commodity prices resulted in a proso millet being the least profitable crop at Sidney, while corn was the most profitable grain crop at Akron and showed net returns that were similar to those found for the forage crops. The results of this study may guide the selection of a spring- or summer-planted crop and help farmers assess risk as they contemplate intensifying the WF system by using a measure or estimate of PAW at planting.