Net Returns from Eight Nonirrigated Cropping Systems on Clay Soil

Considerable research has been conducted on the agronomic relationships of cropping systems adapted to the clay soils of the lower Mississippi River floodplain (30°–37° North latitude); however, only a few studies included the determination and evaluation of net returns. An 8-yr study (1984–1991) was conducted on a Tunica clay (clayey over loamy, montmorillonitic, nonacid, thermic Vertic Haplaquept) to determine net returns above specified costs from eight nonirrigated cropping systems. The cropping systems included 1) monocrop corn (Zea mays L.); 2) monocrop soybean [Glycine max (L.) Merr.]; 3) monocrop grain sorghum [Sorghum bicolor (L.) Moench.]; 4) biennial rotation of corn and soybean; 5) biennial rotation of grain sorghum and soybean; 6) continuous wheat (Triticum aestivum L.)-soybean doublecrop; 7) biennial rotation of corn and wheat-sobyean doublecrop; and 8) biennial rotation of grain sorghum and wheat-soybean doublecrop. Cropping systems that included grain sorghum as a component produced the highest average net returns. Average net returns per acre from grain sorghum-soybean ($76), grain sorghum and wheat-soybean doublecrop ($64), and monocrop grain sorghum ($60) systems were significantly higher than from the monocrop soybean ($25), monocrop corn ($−9), and corn and wheat-soybean doublecrop ($16) systems. Average net returns per acre from the wheat-soybean doublecrop ($48) and the corn-soybean ($42) systems were similar and in the intermediate range. Data indicate that monocrop corn and soybean systems and the corn-wheat-soybean system are not profitable when grown in nonirrigated environments on clay soils in the lower Mississippi River alluvial plain. Research QuestionClay soils occupy approximately 9.6 million acres in the lower Mississippi River floodplain. These soils are mainly planted to soybean without irrigation. Grain sorghum and rice are also adapted to these soils, but are planted on less acreage. Assessment of a crop's profitability cannot be made from yield data alone. This study was conducted to determine and compare net returns above specified costs from eight nonirrigated cropping systems. Literature SummaryYields from soybean grown without irrigation on the clay soils are usually low and marginally profitable. Biennial rotations of soybean with corn, and soybean with grain sorghum have produced significant increases in the yields of all crops. Rotational doublecropping, the practice of growing a summer grain crop, such as corn or grain sorghum, followed by a wheat-soybean doublecrop sequence the next year also improved yields. Considerable research has been conducted on the agronomic relationships; however, only a few studies have included the determination and evaluation of net returns from selected cropping systems adapted to the clayey soils of the lower Mississippi River floodplain. Study DescriptionThis field study was conducted without irrigation on a Tunica clay soil near Stoneville, MS, from 1984 through 1991. It included eight cropping systems (treatments) composed of three monocrops, two biennial rotations, one doublecrop, and two rotational doublecrop systems. Treatments were arranged in a randomized complete block design with four replicates. Crop sequences for each treatment are presented in Table 1. Crop varieties, seed rates, and herbicides used are presented in Table 2. Applied QuestionAre the net returns from these alternative cropping systems for the clay soils of the Mississippi River floodplain comparable to or greater than those produced by nonirrigated monocrop soybean? In this nonirrigated study, cropping systems that included grain sorghum as a component produced the highest average net returns (Table 3). Average net returns per acre from grain sorghum-soybean ($76), grain sorghum and wheat-soybean doublecrop ($64), and monocrop grain sorghum ($60) systems were significantly higher than from the monocrop soybean ($25), monocrop corn ($−9), and corn and wheat-soybean doublecrop ($16) systems. Average net returns per acre from the wheat-soybean doublecrop system ($48) and the corn-soybean ($42) systems were similar and in the intermediate range. These data indicate that nonirrigated cropping systems that include grain sorghum as a component result in the greatest average net returns above specified costs for the systems studied. Wheat as a component crop in all wheat-soybean systems produced stable yields and positive net returns in all cropping systems. Yields and net returns from the monocrop corn and soybean systems and the corn-wheat-soybean system were low and erratic and, on average, were insufficient to cover land rental charges. Table 1Crop production sequences (treatments) for corn, soybean, grain sorghum, and wheat grown near Stoneville, MS, from 1984 through 1991. Crop year1984,1986,1985.19871988,19901989,1991Crop productionTreatment no.sequenceSummerWinterSummerWinter1Corn-cornCorn-Corn-2Soybean-soybeanSoybean-Soybean-3Sorghum-sorghumSorghum-Sorghum4Corn-soybeanCorn-Soybean-5Sorghum-soybeanSorhum-Soybean-6Wheat-soybeanSoybeanWheatSoybeanWheat7Corn-wheat-soybeanCornWheatSoybean-8Sorghum-wheat-soybeanSorghumWheatSoybean- Table 2Crop variety, seeding rates, and herbicides used in nonirigated cropping system study near Stoneville, MS, from 1984 through 1991. CropVarietySeedrateHerbicidesCornPioneer3165 30 000 seed/acreAlachlorAtrazineBentazonGlyphosateMetolachlorNicosulfuronSoybeanBraxton130 000 seed/acreDinosebGlyphosateLinuron + 2,4-DBMetolachlorAsgrow 5980130 000 seed/acreMetribuzinPioneer 9592130 000 seed/acrePendimethalinSorghumPioneer 8333100 000 seed/acreAtrazineDinosebGlyphosateMetolachlorWheatCoker 9543100–120 lb/acre -- Table 3Net returns (RET) above specified expenses for eight nonirrigated cropping systems (TRT†) on clay soil near Stoneville, MS, from 1984 through 1991. RETTRT19841985198619871988198919901991Avg.----------------------- $/acre ----------------------------1 543 16 65−15532−20−61−92−35 5−87 4−15177 31118253 7994−14106−37107 93 52604−332 52 94−135149 60 864255010−29107−101501371957663274−10 17106149 4 8487 876 42 87−152110−99 521684160 10 78−7182 78 6764LSD 0.054447 50 54 13 91 53 3929†Cropping systems are as follows: 1 = monocrop corn; 2 = monocrop soybean; 3 = monocrop sorghum; 4 = biennial rotation of corn-soybean; 5 = biennial rotation of sorghum-soybean; 6 = continuous wheat-soybean doublecrop; 7 = biennial rotation of corn and wheat-soybean doublecrop; 8 = biennial rotation of sorghum and wheat-soybean doublecrop.