Modeling Barley Yield in a Dark Brown Chernozem after Discontinuation of Long‐term Manure Application

Abstract

Core Ideas Soil properties at the discontinuation of manuring adequately explained subsequent grain yield. Soil TOC, TP, TN, and NO3–N were most influential and consistent in explaining yield variability. No evidence of convergence in grain yield among the discontinued manure treatments after 7 yr. Fertilizer application on soils that have received long‐term manure application is often not necessary and typically not advised for environmental reasons. Soil properties at the discontinuation of manure application may assist in modeling crop yield trends on such soils in subsequent years. The data used in this study were from a long‐term field experiment initiated in 1973 at the Agriculture and Agri‐Food Canada Research and Development Centre in Lethbridge, Alberta. Soil and plant samples were collected annually from 1973 through 2010 from irrigated plots that were cropped to barley (Hordeum vulgare L.) every year. Soil properties measured at the start of the experiment in 1973 were used to model yield in the control plots while soil properties measured at the end of annual manure applications in 2003 were used as predictors in partial least squares (PLS) regressions to model barley yield in subsequent years in plots in which manure application was discontinued. Soil total N, organic carbon, P, and NO3–N concentrations were the most important soil properties for modeling annual barley grain yield in manured soils using PLS regression. Our results indicate that initial measured soil properties can be a useful tool in modeling yearly crop yield. During the 7 yr following discontinuation of manure application, there was no evidence of convergence in grain yield among amendment treatments, reflecting that the soil nutrient levels were above agronomic thresholds for optimum yields. Long‐term monitoring of yield will assist in the development of models for predicting when nutrient application will become necessary.