The residual effects of crop residues on N availability and crop growth are largely unknown. A field experiment was conducted from 1986 through 1988 at Lincoln, NE, to determine the residual effects on no-till corn (Zea mays L.) production and N uptake of 0,50, 100, and 1509'0 of the amount of crop residues produced by the previous crop during the previous 5 yr. These effects were evaluated wit...

A two-year experiment was conducted in the field to measure the combined impact of tilling and N fertilization on various agronomic traits related to nitrogen (N) use efficiency and to grain yield in maize cultivated in the presence of a cover crop. Four years after conversion to no-till, a significant increase in N use efficiency N harvest index, N remobilization and N remobilization efficienc...

Management systems influence soil quality over time. A randomized block design in 2 (tillage system) 3 (crop rotation) factorial arrangement was laid-out to evaluate the impact of tillage and crop rotation (2002–2007) on soil quality. Conventional tillage and No-till were factored into continuous corn, corn–soybean, and corn–soybean–wheat–Cowpea systems. Ten soil cores were collected at 0–7.5, ...

In Washington, over fifty percent of the wheat produced under rainfed conditions receives less than 300 mm of annual precipitation. Hence, a winter wheat-summer fallow cropping system has been adopted to obtain adequate moisture for winter wheat production. Current tilled fallow systems are exposed to significant soil degradation from wind and water erosion. As a result, late-planted no-till fa...

Variable rate application of fertilizer has the potential to improve nutrient use efficiency, improve economic returns, and reduce negative environmental impacts. The objective of this study was to evaluate the variable rate application of potassium fertilizer to soybean crop in a no-till system. The study was conducted on a 13-ha soybean grain field in Carambeí, State of Paraná, Brazil in a Ty...

Soil microbial properties are known to exhibit high spatial and temporal variability, which can hinder our understanding of the effects of agricultural management on soil microbial activities, populations and communities. However, if this variability is explicitly considered in soil sampling schemes, experimental results can help us better understand soil microbial properties. In this initial a...

Stratification of nutrient availability, especially of P, that develops with continuous no-till (NT) can affect runoff nutrient concentration and possibly nutrient uptake. The effects of composted manure application and one-time tillage of NT on the distribution of soil chemical properties, root colonization by arbuscular mycorrhizae (AM), and plant P uptake were determined. Research was conduc...

As the world's population increases, marginal lands such as drylands are likely to become more important for food production. One proven strategy for improving crop production in drylands involves shifting from conventional tillage to no-till to increase water use efficiency, especially when this shift is coupled with more intensive crop rotations. Practices such as no-till that reduce soil dis...

No-till cropping is an option for growers needing to reduce soil erosion in the Palouse annual-cropped region of the Pacific Northwest, which is well suited for wheat production. A 6-yr field study was conducted to determine optimum levels of fertilizer and herbicide inputs in a no-till continuous wheat crop production system. Three levels of nitrogen (N) and two weed management levels (WML) we...

x CHAPTER 1 GENERAL INTRODUCTION 1 1.