cover crops soil nutrients roots soil fertility herman warsaw organic agriculture history cities urban ecology soil biology cover crops organic sulfur organic soil management organic farming agriculture nutrient management calcium magnesium soil fertility strip-till hybrid corn history precision no-till agronomy potassium soil organic matter ammonium nitrate soil tilth ia steve berger precision agriculture gps guidance illinois natural resources history ridgetill illinois ecology illinois geology organic cover crops minnesota organic weeds cultivation bioherbicide economics agmasters conference agriculture mechanization crop roots soil water soil erosion organic weed management soil quality cover crops corn soybean calcium magnesium nitrogen sustainable agriculture container gardening farmland preservation ammonia nitrogen fertilizer local food soybeans weed management micronutrients secondary nutrients soil acitid sir albert howard ecology soil testing biofuel sunflower on-farm processing canola
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