the relationships between topography and crop yield. Graveel et al. (1989) observed that corn yields were The purpose of this study was to relate the temporal and spatial more variable on steep slopes but found no significant variability of corn (Zea mays L.) grain yield on a Typic Fragiochrept soil on a hillslope to soil properties and topographic features. Corn differences for degree of slope...

Most current research on winter wheat (Triticum aestivum L.) focuses on increasing yields of either grain or plant biomass. Increased production costs and environmental awareness will promote the development of methods to increase the efficiency of applied nutrients. Nitrogen (N) is often the most limiting nutrient for cereal grain production and represents one of the highest input costs in agr...

This study examines three alternative models of correcting for heteroskedasticity in wheat yield: the time trend variance, the GARCH, and an econometric model that includes the potential sources of heteroskedasticity. Nonnested test results suggest that modeling the sources of heteroskedasticity is the preferred procedure. Including potential sources of heteroskedasticity as explanatory variabl...

Knowledge of production-system performance is largely based on observations at the experimental plot scale. Although yield gaps between plot-scale and field-scale research are widely acknowledged, their extent and persistence have not been experimentally examined in a systematic manner. At a site in southwest Michigan, we conducted a 6-y experiment to test the accuracy with which plot-scale cro...

The objective of this study was to determine how harvest maturity of whole-crop cereals commonly used in swath grazing systems in western Canada affects yield, chemical composition, and in situ digestibility. We hypothesized that the increase in yield with advancing maturity would not offset the decline in digestibility and, thus, the yield of effectively degradable DM (EDDM) would decline with...

The rice-wheat rotation system is an important planting in the middle and lower reaches of Yangtze River. Studies on effects different rice methods water, energy, carbon footprints subsequent wheat have rarely been reported. In this study, cultivation practices were investigated among systems including dry direct-seeded (DSR)-wheat rotation, wet (WSR)-wheat transplanted rice(TPR)-wheat rotation...

In 1996, an effort began to quantify soil water storage, crop use, and productivity on dryland systems in western Kansas. Research 4-year rotations with wheat grain sorghum was initiated at the Southwest Research-Extension Center near Tribune, KS. Rotations were wheat-wheat-sorghum-fallow (WWSF), wheat-sorghum-sorghum-fallow (WSSF), continuous (WW). Soil planting averaged about 9 in. following ...

Wheat is the main food for the majority of Iran's population. Precise estimation of wheat yield change in future is essential for any possible revision of management strategies. The main objective of this study was to evaluate the effects of climate change, CO2 concentration, technology development and their integrated effects on wheat production under future climate change. This study was perf...

Wheat grown in Mn-deficient soil has been widely observed to produce much reduced yields. Breeding for Mn-efficient wheat genotypes adapted to Mn-deficient soils would represent a long-term solution for wheat agronomy. To characterize the physiological basis of Mn efficiency in wheat genotypes would facilitate the breeding programs for producing Mn-efficient wheat. Using a solution culture and ...