Government program changes in the US and Canada during the past five years have increased the need to add more crop diversity to crop/livestock operations. Crop rotation, a planned sequence of crops grown in succession on the same field over an extended time, is the key to managing and developing sustainable no-till systems. The more dissimilar the crops and their cultural practices are in a crop production system, the less opportunity a particular weed or disease species has to become dominant (Lyon et al., 1996; Cook, 1990). Certain grain and forage crops have been known to reduce or eliminate weeds when put in cereal based crop systems (Dryden et al., 1983; Beck and Doerr, 1992). The diversity of the grain and forage crops in the crop system determines how well pests can be managed.
Information is needed on what alternative grain and forage crops can be added to crop production systems to increase plant diversity for better control of disease, insects, and weeds. Since these are crop production systems, we also need to know something about the impact an alternative crop has on soil chemical, physical, and biological processes as well as on succeeding crops. The objectives of our studies were to determined if annual forage crops could provide economic returns that would compare with spring wheat, develop a residue conserving management practice for the production of alternative, crops using small grain equipment, and evaluate the influences of annual forage and alternative, crops on succeeding cereal crops.
The studies were conducted from 1995 through 1996 on fields at the Northern Great Plains Research Laboratory and the Area IV SCD-ARCL; Cooperative Research Farm near Mandan, ND. The soil was a Temvik-Wilton silt loam. Studies were divided into forage and grain crops.
Forage Crops
-Forage crop studies were conducted in 1996 and planted after both sunflower and spring wheat crops. Forages after sunflower were: annual alfalfa (Sava Snail), lentil (CDC Richly), sudan grass (Piper) and foxtail hay millet (Siberian). Spring wheat (Amidon) was included for economic comparison. Forages after spring wheat were: lentil, sudan grass, millet, oat/pea mix, semi leafless pea (Profi), and vine pea (Arvia). All crops were seeded with a Kirschman grain drill in 6-inch rows into minimum-till residue management fields. Eighty pounds N per acre was broadcast and 10 pounds P per acre was placed with the seed at planting. Forage samples were taken when dry matter production was the highest without sacrificing quality. Local prices to calculate gross returns were obtained in early December of the crop year.
Grain crops were seeded in a three-year spring wheat -winter wheat-altemative crop system. Studies began in 1995. Canola (Reward), crambe (Meyer), dry pea (Profi), dry bean (Black Turtle, Shadow), safflower (Montola 2000), soybean (Interstate Payco 9206), and sunflower (Pioneer 6339 in 1995 and Cenex 803 in 1996) were seeded with a JD750 no-till drill into a field where Sonalan (lb ai/a) had been applied and incorporated in a one-pass minimum-till operation with an undercutter. Fertilizer (60 lb N/a and 10 lb P/a) and appropriate inoculum were applied at seeding. Alternative crops were harvested with small grain equipment, except for sunflower where an all crop header was used. Spring wheat was seeded the year after alternative crops using no-till techniques. Local crop prices for mid-November of the year the crop was grown was used to calculate gross returns.
Precipitation during the study was greater than the long-term average for all months except June 1995 and August, 1996 (Table 1). The above average precipitation for July would tend to favor late season crops such as lentil, sudan grass, millet, dry bean, soybean, and sunflower. Results and discussion will be divided into Forage Crops and Grain Crops.
Table 1. Monthly growing season precipitation for 1995, 1996,and long-term (1914-1996) average at Mandan, ND.
Month 1995 1996 Long-Term Average
May 5.4 2.2 2.2
June 1.4 3.4 3. 4
July 6.7 3.2 2.6
August 2.0 1.6 1.7
TOTAL 15.5 10.4 9.7
Annual forage crops had greater production and gross returns when seeded after spring wheat than after sunflower (Figure 1). This could be due to less soil water at forage crop seeding on sunflower stubble. Sunflower uses water and nutrients to a depth of 5 to 6 feet compared to spring wheat which uses water and nutrients to a depth of 4 to 5 feet. During the winter of 1995-1996 (September through April), 4.7 inches of precipitation was received compared to the long-term average of 6.7 inches (Data not shown). 'The greater water use by sunflower along with below average winter precipitation resulted in less water in the soil profile for forage crop production. During winters that have high snowfall, sunflower stalks can hold the snow and make a significant contribution to soil water storage for the next years crop.
Forage hay yield after sunflower was the greatest for sudan grass (4640 lb/a) and lowest for annual alfalfa (988 lb/a) (Figure 1). Among forage crops, seed yield was the greatest for lentil (1123 lb/ac) and lowest for annual alfalfa (311 lb/a). Gross dollar returns for hay ranged from a low of $44/a for annual alfalfa to a high of $76/a for millet. These gross returns are much lower than the gross returns of $120/a for spring wheat grain. Seed from these annual forages resulted in greater gross returns per acre than hay, with the greatest return for annual alfalfa ($218/a). Gross returns per acre for alfalfa and lentil seed yield were greater than returns for spring wheat grain ($120/a).
A greater number of forage crops were evaluated after spring wheat because of the disease potential associated ,with pea and oat/pea crops seeded after sunflower. Hay yield was greatest for sudan grass (5373 lb/a) and lowest for lentil (2079 lb/a). Gross returns for hay was the greatest for vine pea ($130/a) and lowest for lentil ($68/a). Seed yield from the annual forages ranged from 2665 lb/a for vine pea to 368 lb/a for sudan grass. Gross returns for seed were equal to or greater than spring wheat ($136/a) for lentils ($219/a), oat/pea $131 /a), leafless pea ($163/a), and vine pea $178/a).
Gross returns for annual forages after sunflower and spring wheat made it evident that some crops should be grown for forage and some for seed. Lentil, for example, had a seed value three times the hay value, therefore, lentil harvested for seed is better than for hay. For each acre of lentil grown for seed, one could buy almost 2 acres of the other forages grown for hay. The reverse would be true for a crop such as sudan grass.
Seed yield for alternative crops grown in 1995 and 1996 suggest that dry pea, sunflower, and dry bean produced yields that resulted in the greatest gr6ss returns (Figure 2). One has to remember that growing season precipitation was greater than the long-term average and that July precipitation was much greater than would be expected for both years. This would favor the warm season crops. During years when July and August precipitation might be average or above-average, safflower may produce better yields than in 1995 and 1996.
In a systems approach, the alternative crop's impact on a succeeding crop needs to be evaluated. Spring wheat grain yield and gross returns after the 1995 alternative crops were the best where the previous crop was dry pea (56 bu/a; $216/a) and least where the previous crop was sunflower (42 bu/a; $163). Where the previous crop canola, crarnbe, dry bean, or safflower the spring wheat grain yields (50 bu/a) and gross returns ($200/a) were about the same. Spring wheat after an alternative crop produced greater yields (at least 42 bu/a) and gross returns than spring wheat after spring wheat. (Figure I of the adjacent Forage Crops experiment, 35 bu/a.)
How the overall spring wheat-winter wheat-alternative crop system performs in terms of gross returns can be an important factor. All systems produced close to $300/a or more for the two years of data shown in Figure 2. Greatest gross returns were where dry pea was the alternative crop. This will not always be the case because of fluctuating commodity prices and weather. Therefore, one way to add diversity to cereal based cropping systems is to plant two or more alternative crops that are greatly different. This not only spreads out the work load but reduces the risk of a total crop failure.
Beck, D. L., and R. Doerr. 1992. The systems management approach to no-till - Dakota Lakes Research Farm update. Pp. 115-126. In: Proceedings of the 14th Annual Manitoba-North Dakota Zero-Tillage Workshop, Manitoba-North Dakota Zero-Till Assoc.
Cook, R. J. 1990. Disease caused by root-infecting pathogens in dryland agriculture. Adv. Soil Sci. 13:215-239.
Dryden, R. D., L. D. Baily, and C. A. Grant. 983. Crop rotations at the Brandon Research Station: 1893-1982. Pp. 198-210. In: Proc. Annual Manitoba Society of Soil Science Meeting., Winnipeg. University of Manitoba, Winnipeg.
Lyon, D. J., S. D. Miller, and G. A. Wicks. 1996. The future of herbicides in weed control systems of the Great Plains. J. Prod. Agric. 9:209-215.
Figure 1. Annual forage crop production and gross returns for hay and seed when grown after sunflower and spring wheat.
Figure 2. Alternative crop seed yield and gross returns for 1995 and 1996, spring wheat grain yield and gross returns after the 1995 alternative crops, and system gross returns for 1995 and 1996.