Organic and Other Management Strategies with Two- and Four-Year Crop Rotations in Minnesota

Abstract

are many reasons for this, among them the development of effective fertilizers and pesticides, government poli-In the USA, the corn (Zea mays L.)-soybean [Glycine max (L.) cies, and favorable economics. Interest in developingMerr.] rotation depends on high levels of external inputs. Few research data exist comparing conventional production practices with practices alternatives to the present agricultural system has arisen involving reduced external inputs and expanded rotations. Two trials from a number of environmental, economic, and social initiated in 1989 near Lamberton, MN, evaluated a 2-yr corn-soybean issues, including heightened concern over water quality, rotation and a 4-yr corn-soybean-oat (Avena sativa L.)/alfalfa (Medincreased reliance on government subsidies, and a conicago sativa L.)-alfalfa rotation under four management strategies. tinued decline in rural populations. The four management strategies were zero (ZI), low (LI), high (HI), Agricultural productivity gains since the 1950s reand organic (OI) inputs. One trial (V1) was on land with a history sulted from the development of farming systems that of no fertilizer and pesticide usage. The other trial (V2) was on land rely heavily on external inputs of energy and chemicals with a history of conventional fertilizer and pesticide usage. From to replace management and on-farm resources (Oberle, 1993 through 1999, average corn yield in the 2-yr HI strategy was 1994). Continuous rotation of corn and soybean cannot 8.96 Mg ha Ϫ1 in V1 and 8.72 Mg ha Ϫ1 in V2. Corn yield in the 4-yr HI strategy was 4% less than in the 2-yr HI strategy in V1, whereas be sustained without substantial additions of fertilizer in V2, the yields were not different. Soybean yield in the 2-yr HI and pesticides (Heichel, 1978; Pimentel et al., 1978). A strategy was 2.90 Mg ha Ϫ1 in V1 and 2.74 Mg ha Ϫ1 in V2. Soybean number of research studies have been conducted comyield in the 4-yr compared with the 2-yr HI strategy was 3% greaterparing conventional corn-soybean production systems in V1 and 6% greater in V2. These results suggest soybean was more with low-input and organic production systems, includresponsive than corn to the expanded rotation length in the HI strating those by Chase and Duffy (1991) and Karlen et al. (1995) in Iowa, Munn et al. (1998) in Ohio, Liebhardt strategy was 9% less in V1 and 7% less in V2 while soybean yield in et al. (1989) in Pennsylvania, Smolik and Dobbs (1991) the 4-yr OI strategy compared with the 2-yr HI strategy was 19% less and Smolik et al. (1995) in South Dakota, and Posner in V1 and 16% less in V2. These results suggest that yield of organically et al. (1995) and Mallory et al. (1998) in Wisconsin. produced soybean was reduced to a greater extent than that of organically produced corn relative to conventional production practices. By egy. Corn yield in the 4-yr OI strategy compared with the 2-yr HIThe economics of organic grain and soybean production comparing yields of the 2-and 4-yr rotations for each management from several stud...

The environmental impact of recombinant bovine somatotropin (rbST) use in dairy production

“…Adjustment factors of 0.92, 0.92, and 0.83 were used to model crop yields from corn grain/silage, alfalfa, and soybeans, respectively, compared with conventional crop production (www.ers.usda.gov/Data/ARMS/app/Crop.aspx; ref. 40).…”

Soil fertility and crop yields in long-term organic and conventional cropping systems in Eastern Nebraska

“…Compared with conventional cropping systems, reduced yields were reported for most crops in organic systems 1,2,5,6 , whereas some organic systems produced equal or greater yields 3 . Yield differences between the two cropping systems are often crop specific.…”

“…Spurred on by concerns about increasing farm size, environmental pollution, reduced biodiversity across the landscape and increased consumer demand for organic products, investigators have reported on long-term studies of differences between conventional and organic cropping systems [1][2][3][4][5][6] , often with contradictory results. Compared with conventional cropping systems, reduced yields were reported for most crops in organic systems 1,2,5,6 , whereas some organic systems produced equal or greater yields 3 .…”

A Review of Long-Term Organic Comparison Trials in the U.S.

“…The (Porter et al 2003). Two crop rotations and four management strategies are included in the trial, resulting in eight distinct crop management systems.…”