Y variability for a given crop differs geographically and depends on soil type and quality, climate, and the use of irrigation. Yield variability is often measured by an indicator known as the “coefficient of variation,” which measures randomness relative to the mean (or average) value in the yield series. Using this measure, variability in corn yields, for example, ranges from about 0.2 to abo...

Background: To mitigate climate impacts associated with energy consumption, renewable fuel policies have been established in the USA that encourage production and use of corn ethanol. Current fuel usage of corn ethanol is approximately 15 billion gallons/year (57 billion liters/year), with nearly all of this in the form of E10 (10% blend in gasoline). There is now interest in increasing fuel et...

A comparison of decision rules has been made for case studies of corn production using subsurface drip irrigation under three agricultural management practices (no irrigation, uniform irrigation, and variable rate irrigation). The uniform irrigation strategy appeared to perform the best than the other two management practices under different risk scenarios.

A water use simulation for citrus (Citrus sinensis) was used to estimate the effects of climate, soil-available water, rooting depth, allowable depletion of available water, and partial coverage irrigation on the annual irrigation requirements. The soil in the study was excessively drained Candler sand (hyperthermic, uncoated Typic Quartzipsamments) of the Central Florida Ridge. Variation of an...

Although water is crucial to the performance of preemergence herbicides, pesticide performance has rarely been related to irrigation management. This 2-yr study investigated the effect that amount of irrigation water applied had on activity of simazine. Three rates of simazine at 0, 1.12, and 2.24 kg/ha were applied to a 3-yr-old nectarine orchard that was irrigated with microsprinklers. The pe...

Groundwater seepage contributes to irrigation return flows and surface waters. Knowledge of phosphorus (P) concentrations and loads in percolation water that enters the vadose zone and groundwater is necessary to assess and manage water quality. We measured the P in water leached below the crop root zone in a furrow-irrigated Pormeuf silt loam. Vacuum operated percolation samplers were used to ...

Leaching of NO3-N from agricultural lands often occurs in well-defined hot spot areas when viewed across geographical regions of hundreds or thousands of km 2 and often appears as areas of high NO3-N concentrations in shallow underlying aquifers. Delineation of high-NO3-N zones can be achieved by combining models such the Nitrate Leaching and Economic Analysis Package (NLEAP) with Geographical ...

Winter cover crops have the potential to increase soil organic C in the corn (Zea mays L.)–soybean [Glycine max (L.) Merr.] rotation in the upper Midwest. Management effects on soil C, however, are often difficult to measure because of the spatial variation of soil C across the landscape. The objective of this study was to determine the effect of oat (Avena sativa L.), rye (Secale cereale L.), ...

Problem statement: This experiment was carried out for study the effects of chemical and biological fertilizers and interaction between them on some physiological characteristic and yield and its components of seed corn in two different irrigation. Approach: The experiment was conducted in a split plot factorial with completely randomized block design using four replications. Sub plots consiste...