Interseeded Forage Legume Potential as Winter Ground Cover, Nitrogen Source, and Competitor

Abstract

Legume winter ground covers may contribute to row crop systems by providing protection from wind and precipitation and by releasing N to the subsequent row crop, but to attain effective size, these legumes must begin growth well before the winter. A 3‐yr study was conducted to evaluate the performance of four commonly used forage legumes interseeded into corn (Zea mays L.). Alfalfa (Medicago sativa L.), yellow sweetclover (Melilotus officinalis Lam.), red clover (Trifolium pratense L.), and alsike clover (T. hybridum L.) were seeded in a mix consisting of equal seed numbers (pure live seed) from each species. Seeding dates were (i) at corn planting and (ii) at last cultivation. Control treatments were nonseeded. Two levels of weed control also were evaluated. In addition to the factorial experiment, the four species were seeded separately in other corn plots. The herbicide EPTC was also evaluated for use in interseeding. In drier than normal seasons (summer of 1984 and spring of 1985), soil moisture was significantly depleted under interseedings; this depletion was not observed in seasons of normal precipitation. Legume stands and ground cover reflected moisture and light conditions during establishment. In the 2 yr that rows were oriented east‐and‐west, stands conformed to a skewed modal distribution across the inter‐row. Alfalfa and sweetclover usually were better established and produced more cover than either red or alsike clover. Corn yields were not significantly reduced by interseeding per se, but they were reduced when interseeding at the early date interrupted weed control. In treatments that used the herbicide, corn yields were greater than where herbicide was not used, but yields were still significantly below those of the nonseeded control. Research Question Row crop producers around the USA are examining methods of protecting the soil between harvest and planting, and winter cover crops are one alternative receiving interest. Cover crops, by sequestering soil N, also reduce leaching of N below the rooting zone, and legume covers can fix additional N that may be used by row crops in the rotation. Farmers considering the practice need to know: appropriate cover crop species for their area; the most economical and effective methods for establishing the cover crop; and how to manage the cover crop to avoid competition with the row crop. This project was designed to answer those questions relative to use of forage legumes as cover crops following corn under mid western conditions. Literature Summary Research on cover crops in corn has often found that practices that favored cover crops (e.g., wide rows, earlier seeding dates) decreased corn yield. Corn yield can also be decreased by competition from weeds associated with cover cropping. While weed control is a real issue, weed effects on the row crop should be understood as a question separate from effects of the cover crop itself. Study Description The study was conducted over 3 yr on a farm in central Iowa. Soils were loam, clay loam, and silty clay loa...

Living Mulch as a Tool to Control Weeds in Agroecosystems: A Review

“…Living mulches differ in their ability to establish well in an interseeding situation. For example, Exner and Cruse (1993) found that alfalfa (Medicago sativa L.) and sweet clover (Melilotus officinalis L.) usually established better and produced more cover than either red clover (Trifolium pratense L.) or alsike clover (T. hybridum L.) when interseeded under corn. The competitive ability against weeds is also another important characteristic determining the suitability of a plant species as a living mulch.…”

Effects of Intercropping on the Performance of Maize and Cowpeas in Botswana

“…Legume intercrops are a potential source of plant nutrients that compliment/supplement inorganic fert ilizers [17]. Legu me intercrops have several socioeconomic [18], and biological and ecological [19,20,21,22,23] advantages compared to sole cropping for small-holder farmers [24]. In addition, certain legumes crops provide food to humans and livestock [17].…”

Suitability of legume cover crop-winter wheat intercrops on the semi-arid Canadian Prairies

“…1). Previous studies have similarly reported that alfalfa is more competitive with weeds than red clover under semi-arid conditions (Exner and Cruse 1993;Schlegel and Havlin 1997).…”