Alternative Cropping Systems on Dry and Irrigated Land
The small grain summer fallow/dryland cropping system was originally developed to conserve water and nutrients in one year for use in the next. However, inefficiencies in storing water under fallow, development of effective chemical weed controls and increased use of nitrogen fertilizers have led to a reduction in summer fallow and a rise in continuous (without fallow) cropping in some areas. Over the past 25 to 30 years, research in the Great Plains has shown that the long-standing practice of alternating summer fallow with spring wheat production is inefficient in storing soil water (Greb, 1979; Greb et al., 1979), has caused the formation of saline seeps (Brown et al., 1983; Diebert et al., 1986), and promotes soil organic matter (OM) loss (Haas et al., 1957). Comparisons of wheat-fallow systems with more intense dryland rotations in the region every year have shown greater water-use-efficiencies and resulted in biological yield advantages over wheatfallow (Peterson et al., 1996; Anderson et al., 1999; Nielsen et al., 1999).
Similar work has been done at Sidney (Aase and Reitz, 1989) with the stipulation that greater cropping intensity be accompanied by a reduction in tillage intensity to allow crop residues to remain on and below the soil surface. The introduction of minimum till or zero-till continuous cropping practices further conserves soil water, provides improved microenvironments for seedlings and soil biota, and increased precipitation use efficiencies (Farahani et al. 1998). Furthermore, weed management has always been an economic and environmental problem in agriculture, but control options are especially limited on low value crops (Tanaka 1989).
The use of integrated crop production systems (ICPS), with multiple alternative crop options and rotations, increases the biological diversity of crops and soils. This "biologically dynamic" approach is advantageous to overall production in both the central (Nielsen, 1998; Anderson et al., 1999) and northern Great Plains (Johnston et al., 2002; Aase and Pikul, 2000). Greater biological diversity in
arotation disrupts pest cycles and promotes more efficient use of soil water and nutrients (Vigil et al., 1997). Viable alternatives to small grains (within the context of crop rotations) include pulse and oilseed crops; however, specific research is needed to examine many of the crop interactions occurring within this context (Miller et al., 2002; Johnston et al., 2002).
Successful design of rotations for the region requires an understanding of previous-crop water and nutrient use, and its effects on following crops (Nielsen and Anderson, 1993; Westfall et al., 1996). Tanaka et al (2002) presented a framework for "dynamic" cropping systems that utilizes a variety of soil and plant management practices (with a diversity of crop species) to reduce the risk of disease, weeds and insects. While these concepts were developed for dryland production systems, they should also apply to irrigated cropping systems.
Contributing Scientists: Robert Evans (Agricultural Engineer), Jed Waddell (Soil Scientist), Andrew Lenssen (Weed Ecologist), TheCan Caesar-TonThat (Microbiologist), Upendra Sainju (Soil Scientist), Robert T. Lartey (Plant Pathologist), Bill Iversen (Physical Scientist), James Kim (Post Doctoral Research Associate), Jay Jabro (Soil Scientist) and Bart Stevens (Agronomist) Latest Research Findings/Reports Yield, Quality, Water Use, and Weeds in Annual Forage-Spring Durum Cropping Systems Effect of Phosphorus Fertilization Rates on Field Pea Nitrogen Production
By: A. Lenssen, G. Johnson, P. Hatfield, D. Cash, & S. Blodgett
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Diversified, intensified rotations with annual forages replacing summer fallow can increase overall rotational productivity, but even if rainfall is normal, durum grain yield losses do occur compared to durum following fallow. Also, annual forages replacing summerfallow have reduced water use compared to durum and some annual forages produced without in-crop herbicides do not increase weed densities in the subsequent crop. This practice, however, requires additional research at other locations with different predominant weed communities.
By: Jed Waddell and Andy Lenssen
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Field pea acreage in Montana has nearly quadrupled since 1997 because of suitability to the climate and soils of the region and changes in the farm program. Usually in rotation with cereals, field pea provides a means to manufacture nitrogen from the atmosphere by nodulation with Rhizobium leguminosarum. This study attempts to determine whether P fertility has an impact on nitrogen production by the pea crop and the amount of N contributed to the following spring wheat crop. First year results suggest that increased P fertility increases pea yield and protein but has a limited effect on N in residue.
Latest Research Findings/Reports
Yield, Quality, Water Use, and Weeds in Annual Forage-Spring Durum Cropping Systems
Effect of Phosphorus Fertilization Rates on Field Pea Nitrogen Production