Crop and Soil Response to Long-Term Tillage Practices in the Northern Great Plains

Summer fallow is the most common cultural practice in the northern Great Plains. With proper cultural management, however, annual cropping may be feasible and economical. Our objective was to determine crop and soil response to nontraditional annual cropping practices (till and no-till) in lieu of conventional fallow-crop rotation for the production of spring wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) in the northern Great Plains. The study, initiated in 1983, was on a Dooley sandy loam (fine-loamy, mixed Typic Argiboroll) 11 km north of Culbertson, MT. Tillage practices on annually cropped treatments included sweep tillage in autumn and disk tillage in spring; sweep tillage in spring; and no-tillage. Conventional fallow-spring wheat rotations were included as the control. With three exceptions, there were no statistical differences among treatments in soil P, soil nitrate N, and pH. Phosphorus and N were nonlimiting in all years; pH decreased about 0.06 units per year in the 0- to 8-cm layer because of N fertilization. Bulk density differences in the 0- to 10-cm layer appeared after 7 yr, with the lowest bulk density for the no-tillage annual crop treatment. Grain and straw yields with the no-tillage treatment were both 80% of yields with the fallow-crop treatment. Total water use efficiency, based on soil water differences between harvest of one crop and harvest of the next, was significantly greater with no-tillage than with the fallow-crop treatment. Soil organic C decreased nearly 0.4 g kg I per year with the fallow-crop treatment; there was a negligible decline with the no-tillage annual crop treatment. No-tillage annual spring wheat crop production was the most efficient crop and soil management practice from the standpoint of yield, water use efficiency, soil organic C, and bulk density

Lentil water use and fallow water loss in a semiarid climate

With renewed interest in legumes for green manures or as partial summer fallow replacement crops, it is important to know water requirements of these crops in semiarid agriculture. Our objective was to evaluate seasonal water use by black lentil (Lens culinaris Medikus cv. Indianhead), a potential fallow replacement crop, and to relate water use to parameters useful as soil water management tools. We measured evapotranspiration (ET) from two precision weighing lysimeters located on a Williams loam (fine-loamy, mixed Typic Argiboroll) near Sidney, MT. The lysimeters were in adjacent 180- by 180-m fields in a typical strip-crop environment of the semiarid northern Great Plains. Bowen ratio estimates of ET were also obtained. Lentil was seeded no-till into wheat (Triticum aestivum L.) stubble on one lysimeter field in 1993, and the other was left in chemical fallow. Seeded and fallow fields were rotated in 1994. Water loss by ET from lentil and fallow lysimeters was the same ( 25 mm) for 3 wk following seeding. Plant height was related to growing degree days (GDD) in both years. Cumulative ET was related to GDD for both years until about 800 GDD, corresponding to nearly 300 mm ET. Deciding how much water to sacrifice (with hopes of recovery during the noncrop period) becomes a matter of judgment about probable rainfall. At full bloom ( 2 Mg ha' dry matter production), the lentil crop used about 50 to 70 mm more water than fallow. Probably no more than 50 mm of water loss above that from fallow should be sacrificed if a grain crop is to be seeded the following year. From a practical standpoint, because plant height was closely related to both GDD and cumulative ET, it is plausible that a simple measure of lentil height (about 350 mm maximum) can give sufficient accuracy for determining when lentil growth, as a partial summer fallow replacement crop in a semiarid climate, should be terminated

One Plus One Equals Three: The Synergistic Effects Of Crop Rotation On Soil Fertility And Plant Nutrition

Corn grown under annual corn-soybean crop rotation has greater accumulation of certain mineral nutrients and higher yields than corn grown in monoculture. This study was conducted to determine if complex crop rotations (with legumes in the rotation as alfalfa hay as well as soybean row crops) and different levels of agriculture chemical input affect soil fertility and corn mineral nutrient composition. The effects of crop rotation [monoculture corn, corn-soybean 2-yr rotation, corn-soybean- wheat underseeded with alfalfa-alfalfa 4-yr rotation] and input level [high input (fertilizer application for 8.15 Mg ha-1 yield goal, prophylactic herbicide and insecticide application, fall moldboard plow/spring disk and cultivation operations), intermediate input (fertilizer application for 5.33 Mg ha-1 yield goal, pesticide applications based upon pest survey and IPM principles, fall chisel plow/spring disk and cultivation operations), and low input (no fertilizer, herbicide, or insecticide applications, fall chisel plow/spring disk and cultivation operations)] on soil fertility (pH, organic matter, NO3-N, P, K, and total N) and on corn shoot dry weight, mineral nutrient (N, P, Ca, Mg) concentration and accumulation at tassel stage of development were investigated at Brookings, SD. Soil samples taken at the V6 stage of corn development indicated that crop rotation treatments reduced soil pH, increased soil NO3-N level, and decreased soil P level when compared to corn monoculture. Shoots of plants grown under either 2-yr rotation intermediate input or 4-yr rotation no input treatments had greater dry weight, as well as greater P, Ca, and Mg accumulation than these same input treatments in other rotations. These results demonstrate a beneficial effect of crop rotation upon soil fertility and corn mineral nutrition. The results of this experiment are discussed in terms of nutrient synergisms whereby nutrient absorption proceeds at a faster rate than dry weight accumulation

Soil Carbon, Nitrogen Use, And Water Use Affected By Rotation In The Northern Corn Belt

Diversified crop rotation may improve production efficiency, reduce fertilizer nitrogen (N) requirements for com (Zea mays L.) and increase soil carbon (C) storage. Objectives were to determine effect of rotation and fertilizer N on soil C sequestration, water use, and N use. An experiment was started in 1990 on a Barnes clay loam (fine-loamy, mixed, superactive, frigid Calcic Hapludoll) near Brookings, South Dakota. Primary tillage on all rotations was with a chisel plow. Rotations were continuous com (CC), com-soybean [Glycine max (L.) Merr.] (CS) and a 4-year rotation of corn-soybean-wheat (Triticum aestivum L.) companion seeded with alfalfa (Medicago sativa L.)-alfalfa hay (CSWA). Additional treatments included plots of perennial warm season, cool season, and mixtures of warm and cool season grasses. N treatments for com were: com fertilized for a grain yield of 8.5 Mg ha-1 (high N), 5.3 Mg ha-1 (midN), and no N fertilizer (noN). Average com grain yield (1996-2001) was not different among rotations at 7.1 Mg ha-1 under highN. Com yield differences among rotations increased with decreased fertilizer N. Average (1996-2001) com yield with noN fertilizer were 7.3 Mg ha-1 under CSWA, 6.1 Mg ha-1 under CS, and 3.8 Mg ha- l under CC. Rotation did not improve N use efficiency (NUE) or water use efficiency (WUE) under highN. With midN, NUE and WUE was about 40% greater under CSWA compared with CC. Plant carbon return depended on rotation and N. In the past 10 years, total C returned from above ground biomass were 29.8 Mg ha-I under CC with highN and 12.8 Mg ha- l under CSWA with noN. Soil C in the top 15 cm significantly increased (0.7 g kg- l) with perennial grass cover but decreased (1.7 g kg- l) under CC, CS, and CSWA. C/N ratio significantly narrowed (-0.75) with CSWA and widened (0.72) under grass. Diversified rotations have potential to increase N use efficiency and reduce fertilizer N input for com. However, within a com production system using conventional tillage and producing (averaged across rotation and N treatment) about 6.2 Mg ha- l com grain per year, we found no gain in soil C after 10 years regardless of rotation

Lentil water use and fallow water loss in a semiarid climate

With renewed interest in legumes for green manures or as partial summer fallow replacement crops, it is important to know water requirements of these crops in semiarid agriculture. Our objective was to evaluate seasonal water use by black lentil (Lens culinaris Medikus cv. Indianhead), a potential fallow replacement crop, and to relate water use to parameters useful as soil water management tools. We measured evapotranspiration (ET) from two precision weighing lysimeters located on a Williams loam (fine-loamy, mixed Typic Argiboroll) near Sidney, MT. The lysimeters were in adjacent 180- by 180-m fields in a typical strip-crop environment of the semiarid northern Great Plains. Bowen ratio estimates of ET were also obtained. Lentil was seeded no-till into wheat (Triticum aestivum L.) stubble on one lysimeter field in 1993, and the other was left in chemical fallow. Seeded and fallow fields were rotated in 1994. Water loss by ET from lentil and fallow lysimeters was the same ( 25 mm) for 3 wk following seeding. Plant height was related to growing degree days (GDD) in both years. Cumulative ET was related to GDD for both years until about 800 GDD, corresponding to nearly 300 mm ET. Deciding how much water to sacrifice (with hopes of recovery during the noncrop period) becomes a matter of judgment about probable rainfall. At full bloom ( 2 Mg ha' dry matter production), the lentil crop used about 50 to 70 mm more water than fallow. Probably no more than 50 mm of water loss above that from fallow should be sacrificed if a grain crop is to be seeded the following year. From a practical standpoint, because plant height was closely related to both GDD and cumulative ET, it is plausible that a simple measure of lentil height (about 350 mm maximum) can give sufficient accuracy for determining when lentil growth, as a partial summer fallow replacement crop in a semiarid climate, should be terminated