The organic farming concept developed in the period prior to 1940 and was pioneered by Sir Albert Howard (1873–1947). Howard, born and educated in England, directed agricultural research centers in India (1905–1931) before permanently returning to England. His years of agricultural research experiences and observations gradually evolved into a philosophy and concept of organic farming that he espoused in several books. Howard's thinking on soil fertility and the need to effectively recycle waste materials, including sewage sludge, onto farmland was reinforced by F.H. King's book,Farmers of Forty Centuries. Howard developed a system of composting that became widely adopted. Howard's concept of soil fertility centered on building soil humus with an emphasis on how soil life was connected to the health of crops, livestock, and mankind. Howard argued that crop and animal health was a birthright and that the correct method of dealing with a pathogen was not to destroy the pathogen but to see what could be learned from it or to ‘make use of it for tuning up agricultural practice’. The system of agriculture advocated by Howard was coined ‘organic’ by Walter Northbourne to refer to a system ‘having a complex but necessary interrelationship of parts, similar to that in living things’. Lady Eve Balfour compared organic and non-organic farming and helped to popularize organic farming with the publication ofThe Living Soil. Jerome Rodale, a publisher and an early convert to organic farming, was instrumental in the diffusion and popularization of organic concepts in the US. Both Howard and Rodale saw organic and non-organic agriculture as a conflict between two different visions of what agriculture should become as they engaged in a war of words with the agricultural establishment. A productive dialogue failed to occur between the organic community and traditional agricultural scientists for several decades. Organic agriculture gained significant recognition and attention in 1980, marked by the USDA publicationReport and Recommendations on Organic Farming. The passage of the Federal Organic Foods Production Act in 1990 began the era of accommodation for organic farming in the USA, followed by another milestone with official labeling as USDA Certified Organic in 2002. Organic agriculture will likely continue to evolve in response to ongoing social, environmental, and philosophical concerns of the organic movement.

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for crop nutrient removal are an important component of nutrient management planning and crop production. Effective nutrient management requires an accurate accounting of Although state agronomy guides and other sources nutrients removed from soils in the harvested portion of a crop. Because the typical crop nutrient values that have historically been used often publish values for crop nutrient removal, the origimay be different under current production practices, a study was nal studies on which those values are based are seldom conducted to measure nutrient uptake in grain harvested in 1998 and cited. Also, the values that were established in the past 1999 from 23 site-years in the Mid-Atlantic region of the USA. There may not be correct for current agronomic technologies were 10 hybrids included in the study, but each site grew only one such as hybrid, higher plant population, yield potential, hybrid each year. Corn (Zea mays L.) production practices followed fertilizer practice, and soil conditions. Furthermore, local state extension recommendations. Minimum, maximum, and there is a need to re-evaluate crop nutrient removal mean corn grain yields were 4.9, 16.7, and 10.3 Mg ha Ϫ1. Nutrient values for corn as several states in the Mid-Atlantic concentrations were determined on grain samples oven-dried at 70؇C USA now mandate the development of comprehensive for 24 h. Minimum, maximum, and median nutrient concentration nutrient management plans (Simpson,

for crop nutrient removal are an important component of nutrient management planning and crop production. Effective nutrient management requires an accurate accounting of Although state agronomy guides and other sources nutrients removed from soils in the harvested portion of a crop. Because the typical crop nutrient values that have historically been used often publish values for crop nutrient removal, the origimay be different under current production practices, a study was nal studies on which those values are based are seldom conducted to measure nutrient uptake in grain harvested in 1998 and cited. Also, the values that were established in the past 1999 from 23 site-years in the Mid-Atlantic region of the USA. There may not be correct for current agronomic technologies were 10 hybrids included in the study, but each site grew only one such as hybrid, higher plant population, yield potential, hybrid each year. Corn (Zea mays L.) production practices followed fertilizer practice, and soil conditions. Furthermore, local state extension recommendations. Minimum, maximum, and there is a need to re-evaluate crop nutrient removal mean corn grain yields were 4.9, 16.7, and 10.3 Mg ha Ϫ1. Nutrient values for corn as several states in the Mid-Atlantic concentrations were determined on grain samples oven-dried at 70؇C USA now mandate the development of comprehensive for 24 h. Minimum, maximum, and median nutrient concentration nutrient management plans (Simpson,

The consensus of soil fertility specialists working in the northeast USA was that soil testing and recommendation systems for P needed to be reexamined because of recent changes in soil testing methodology in the laboratory and corn (Zea mays L.) production technology in the field. Soil tests (M-COL, MM-COL, B-ICP, M1-ICP, and M3-ICP) were performed by either colorimetry or inductively coupled plasma (ICP) emission spectroscopy on samples from soil test calibration studies conducted during 1998 to 1999 at 51 experimental sites chosen to represent a range of soils, including Ultisols, Spodosols, and Alfisols, in northeastern states (Connecticut, Delaware, Massachusetts, Maryland, Maine, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, Vermont, and West Virginia). The mean P measured by M-COL, MM-COL, B-ICP, M1-ICP, and M3-ICP was 8.3, 6.6, 148, 66, and 121 mg P kg 21 , respectively. Production practices followed local state extension recommendations at each site and included P fertilizer treatments: none, 15 kg P ha 21 banded, or 60 kg P ha 21 broadcast. Combined analysis of variance over sites showed that plant height at 35 d after planting, silk emergence, grain yield, and grain dry down were enhanced by the broadcast P treatment. There were yield increases (P , 0.10) to the band treatment at only four sites and to the broadcast treatment at nine sites. Cate-Nelson statistical analysis of relative yield in relation to soil test P failed to identify soil test P critical levels for any of the soil test methods. The percentage of experimental sites that had soil test P levels below the currently used critical levels in the region ranged from 14 to 65% of the sites. Results showed that 17 to 47% of those sites testing below the critical level exhibited a yield increase (P , 0.10) to broadcast P. Some of the yield responsive sites had soil test P above currently used critical levels. The calibration data obtained from the present study and the relationships examined between soil test P and relative yield do not necessarily Abbreviations: B-ICP, Bray-P1 with inductively coupled plasma emission spectroscopy determination of extracted P; M-COL, Morgan with colorimetric determination of extracted P; MM-COL, Modified Morgan with colorimetric determination of extracted P; M-ICP, Morgan with inductively coupled plasma emission spectroscopy determination of extracted P; MM-ICP, Modified Morgan with inductively coupled plasma emission spectroscopy determination of extracted P; M1-ICP, Mehlich-1 with inductively coupled plasma emission spectroscopy determination of extracted P; M3-ICP, Mehlich-3 with inductively coupled plasma emission spectroscopy determination of extracted P; PSNT, presidedress soil nitrate test.