Grain (pulse) legumes could provide high nitrogen (N), late summer forage for stocker cattle in the southern Great Plains (SGP). This study evaluated the forage yield and nutritive value of tropical annual legumes that were relatively uncommon in the SGP, at a site (35°40‘ N, 98°00’ W) in central Oklahoma. Included were cultivars of pigeon pea ([Cajanus cajan (L.) Millsp.], cv. GA‐2), guar ([Cyamopsis tetragonoloba (L.) Taub.], cv. Kinman), cowpea ([Vigna unguiculata (L). Walp.], cv. Chinese red), and mung bean ([Vigna radiata (L.) Wilcz.], cv. Berkins), and grain soybean ([Glycine max (L.) Merr.] cv. Hutcheson) was used as a control. Seeds were inoculated and planted (60‐cm row spacing at 10 seeds m−1 row length) annually in mid‐June 2003 through 2006. Aboveground samples were collected on six dates, from 45 to 120 d since planting. Soybean, pigeon pea, and guar averaged 3560, 3439, and 3321 kg ha−1, while mung bean and cowpea averaged 2918 and 2405 kg ha−1, respectively. Mung bean and cowpea accumulated the least N (70 and 65 kg N ha−1), while soybean, guar, and pigeon pea yielded 100, 93, and 77 kg N ha−1, respectively. Digestibility of cowpea, mung bean, soybean, and guar were similar (757 to 825 g kg−1), while pigeon pea was least digestible (634 g kg−1). These pulse legumes could provide producers in the SGP with options other than soybean for generating forage or biological N.

Forage‐based livestock production is a significant component of the agricultural economy throughout the southern U.S. Great Plains. However, Livestock production in grazing systems is limited by low forage mass and quality from late July to early November. Pigeonpea (Cajanus cajan L. Millsp.) is a warm‐season grain legume that may have potential as a summer forage crop. A 3‐yr (1996–1998) field study was conducted near El Reno, OK, to assess the performance of two early maturing pigeonpea lines, Georgia‐2 and ICPL 85010. The two lines did not differ significantly in forage and grain production and nutritive value. At 96 d after planting (DAP), total aboveground biomass was 5.2 Mg ha−1, N content was 23 g kg−1, and in vitro digestible dry matter (IVDDM) was 580 g kg−1 averaged across years. At final harvest (118 DAP), total dry biomass was 12.6, 6.4, and 9.3 Mg ha−1 in 1996, 1997, and 1998, respectively. Seed yield was 5.4, 1.9, and 1.2 Mg ha−1 in 1996, 1997, and 1998, respectively. Nitrogen concentration and IVDDM at final harvest was 19 and 585 g kg−1 for total plant biomass, 34 and 758 g kg−1 for leaves, 9 and 420 g kg−1 for stems, and 26 and 750 g kg−1 for seed, respectively. Early maturing pigeonpea lines can fill the forage deficit period during late summer and provide protein supplement for livestock.

resources may become inherent to a cropping system, if the system is to be sustainable.Cropping systems will not be sustainable without change. Broad-One problem associated with cropping systems is how scope problems associated with developing sustainable cropping systems are how to choose and sequence crops in cropping systems. Our to choose and sequence crops to develop the inherent objectives were twofold: (i) evaluate impacts of crop sequencing on internal resources of the system while taking advantage precipitation use and (ii) show how crop sequencing can accentuate of external resources such as weather, markets, governsynergistic interactions among crops. Crop-fallow systems that develment programs, and new technology (Tanaka et al., 2002). oped in the Great Plains resulted in precipitation storage efficiencies To better understand and appreciate cropping systems of about 20% in the early 1930s to about 40% in the late 1980s. and the crops used in them, we must consider the evolu-Integrated crop-livestock systems have been developed in the southern tion that crops and cropping systems have gone through. Great Plains to take advantage of bimodal annual precipitation pat-Our goal is to stimulate researchers to think at the systern to produce high quality pigeonpea [Cajanus cajan (L.) Millsp.] tems level when conceptualizing and developing intenforage during the noncrop period between winter wheat (Triticum sive-diverse cropping systems. Our objectives were twoaestivum L.) harvest and seeding. Pigeonpea can be grown after a mid-June winter wheat harvest since pigeonpea uses precipitation received fold: (i) evaluate the impact of crop sequencing on use from wheat harvest to late September and pigeonpea has a root system of precipitation and (ii) show how crop sequencing can that allows it to use soil water below the effective rooting depth of accentuate synergistic interactions among crops in the wheat. In the central Great Plains, water-use efficiency of winter Great Plains.wheat was improved 18 to 56% by including broadleaf crop in a grassbased rotation. Cropping systems in the northern Great Plains tend to be more diverse, and research at Mandan, ND, suggests that seed growth through evapotranspiration, approached 75% for continuous annual cropping systems compared with Published in Agron. J. 97:385-390 (2005). less than 45% for winter wheat-fallow system (Farahani

Stocker cattle production in portions of southern Great Plains depends on wheat (Triticum aestivum L.) and warm‐season perennial grasses. Nutrient supply is limited in both quantity and quality from late July through November. To determine if pigeonpea [Cajanus Cajan (L.) Millsp.] could fill this deficit, a field study was conducted from 1996 to 1998. Seasonal forage production patterns, yield, and quality of three pigeonpea ecotypes (ICP8151, ICPX910007, and PBNA) were evaluated. Pigeonpeas produced 5 Mg ha−1 dry matter by 26 August, with N concentration >20 g kg−1 and digestible dry matter (DDM) > 500 g kg−1 Ecotype ICPX910007 accumulated greatest dry matter in 136 d (16 Mg ha−1), followed by ICP8151 (13 Mg ha−1) and PBNA (9.5 Mg ha−1). Mean N concentration for PBNA was 28.6 g kg−1 as compared with 23.3 and 23.0 g kg−1 for ICP8151 and ICP910007, respectively. Digestible dry matter of PBNA was 614 g kg−1, followed by 576 and 572 for ICP8151 and ICP910007, respectively. Leaf dry matter yield averaged across sampling dates and years for all ecotypes ranged from 2360 to 2600 kg ha−1 Leaf quality was similar to that of alfalfa for all ecotypes. Environmental conditions such as cooler spring and summer temperatures and excess rainfall (1997) or extreme drought (1988) reduced yield of all ecotypes. Pigeonpea can provide high‐quality forage that could be used as a primary or supplementary forage for grazing livestock at a time when other forages are less productive.

from 120 to 140 g kg Ϫ1 for stems, 190 to 200 g kg Ϫ1 for leaves, and 120 to 270 g kg Ϫ1 for pods, depending on Pasture for livestock in the southern Great Plains is often in short the stage of development (Miller et al., 1973). However, supply during the late summer. This study compared seasonal patterns when the value of the oil seed climbed in the 1960s and in forage production, forage quality, and seed yield of three recently developed forage soybean [Glycine max (L.) Merr.] cultivars (Done-1970s, soybean production shifted almost exclusively gal, Derry, and Tyrone) to the seed cultivar Hutcheson. Inoculated to seed cultivars. Many producers are now grazing or seeds were planted at 60 kg ha Ϫ1 in rows (20 m long) with 60-cm harvesting immature soybean fields for hay. Devine and spacing, in June 2001, 2002, and 2003, after harvest of no-till winter Hatley (1998) and Devine et al. (1998) recently develwheat (Triticum aestivum L.). Whole plant samples were collected oped several improved cultivars of forage soybean that on six sample dates from approximately 52 to 120 d after seeding could provide better grazing. (DAS). At 120 DAS, forage soybeans Derry, Donegal, and Tyrone Little research has been conducted on the productivleaf and stem accumulations were 15, 46, and 47% and 43, 69, and ity and value of forage soybean in the southern Great 126% greater than that of Hutcheson, respectively. Seed soybean Plains region. The objectives of this study were to cominitiated flowering 15 d earlier than forage soybeans, resulting in lower leaf and stem yield. Forage quality of whole plants (N concentration pare and quantify leaf, stem, and pod production and and dry matter digestibility) of whole plant was similar across cultivars. the quantity and quality of each component of forage-Seed yield of Tyrone was lowest (690 kg ha Ϫ1 ), as compared to Donegal