Weeds are a major obstacle to successful crop production in organic farming. Producers may be able to reduce inputs for weed management by designing rotations to disrupt population dynamics of weeds. Population-based management in conventional farming has reduced herbicide use by 50% because weed density declines in cropland across time. In this paper, we suggest a 9-year rotation comprised of ...

Most methods used for crop classification rely on the ground-reference data of the same year, which leads to considerable financial and labor cost. In this study, we presented a method that can avoid the requirements of a large number of ground-reference data in the classification year. Firstly, we extracted the Normalized Difference Vegetation Index (NDVI) time series profiles of the dominant ...

A hydroponic system was developed and used for purification of an anaerobically treated dairy manure and production of forage crops. The effect of light duration, seeding rate and wastewater application rate on the crop yield and pollution potential reduction were studied. The results indicated that a wheat forage crop can be produced in 21 days from germination to harvest in this system and re...

Severe food shortage is associated with increased mortality and reduced reproductive success in contemporary and historical human populations. Studies of wild animal populations have shown that subtle variation in environmental conditions can influence patterns of mortality, fecundity and natural selection, but the fitness implications of such subtle variation on human populations are unclear. ...

Hele rodera goeuingiana damages leguminous crops in Europe and the Mediterranean Basin. Il is managed by nematicides and crop rotation. The tolerance level for most hosts is less than one egg/g soil, but is higher for vetch (2 eggs/g soil). Conventional economic thresholds varied with crop value and nematicide cost. For DD nematicide at current priees, threshold levels were 8 and 2.5 eggs/g soi...

This manual is only partially complete and is a work in progress. A completed manual will be available by January 1,2000. Cluster and TreeView are Y2K Compliant because they are oblivious of date and time.

Vertical distributions of (36)Cl and (99)Tc are presented from deep and shallow lysimeters above artificially controlled water tables for a 4-yr experiment from 1990 to 1993. Activity concentration profiles were all measured in late summer when a winter wheat (Triticum aestivum L. cv. Pastiche) crop was harvested. After harvest, activity concentrations in different organs of the crop were deter...

A multinomial fractional logit model is developed in this article to examine the effects of various market variables, commodity and conservation program payments and county physical attributes on crop acreage allocation and CRP enrollment simultaneously in the Midwest region of the United States. Nine states and eleven years county level panel data are employed to estimate the acreage allocatio...

The fruiting ecology of Osyris quadripartita (Santalaceae), a hemiparasitic evergreen shrub, was studied over a 4-yr period in a Mediterranean scrubland of southern Spain. In addition to describing the natural history of seed dispersal in this species, objectives of the study were (1) to document patterns of individual and annual variation in seed-dispersal-related traits (fruit characteristics...

The transfer of genes from crop plants to their wild relatives via hybridization has emerged as one of the primary risks associated with the commercialization of genetically engineered crops. Although previous studies have revealed relatively high levels of hybridization when crop plants come into contact with their wild relatives, the frequency of such contact across the range of cultivation o...