Selection of herbaceous energy crops for sustainable agriculture

Double cropping, a system in which more than one crop is produced per year in a land area, helps to increase food and feed production in the United States. But the impact of double cropping on production of biomass (crops grown to be converted to fuel) has not been evaluated. Such cropping systems have been successful in the eastern and southern United States. If they can be adapted to the relatively short growing season of the extremely large and agriculturally productive north-central region of the United States, biomass production potential can be greatly increased

Production and Quality Characteristics of Forage Soybeans for Livestock Feed

When first introduced into the United States, soybean was used predominately as a summer annual forage legume. Soybean is still consider a viable alternative when supply becomes limiting and additional forage is needed. During the past few years, many forage producers have experienced difficulty establishing alfalfa because of excessively wet or dry springs. Additionally, some loss of established stands has occurred through winter kill. Failure of spring seedings or loss of established stands is usually not apparent until sometime into the growing season. Because of their later planting date than alfalfa, summer annual crops fill an important role in the forage supply of the Midwest. Additionally, the high energy content in soybean lipids (oil) increases the energy density of the forage, which can be of value for supplying the energy needs of high producing ruminants such as lactating dairy cows. In this article, we discuss yield and forage-quality relationships of soybean and point out its potential as feed for ruminant livestock. Because soybean has not been used much for forage recently, such information is limited. First we will make a few introductory comments about forage quality

Effect of Acid Detergent Lignin Concentration in Alfalfa Leaves on Three Components of Resistance to Alfalfa Rust

As plant breeders select alfalfa (Medicago saliva) genotypes for improved digestibility by ruminants, there may be an increased risk of yield losses due to plant disease. This is because increases in digestibility are often associated with a decrease in lignin content and lignin has been shown to play an important role in plant defense mechanisms against disease and pests. The method most often employed by public and private alfalfa-breeding programs to assess digestibility is acid detergent lignin (ADL) analysis. ADL concentration was determined for individual alfalfa plants from two different alfalfa populations. Plants representing a range of ADL concentrations within each population were arbitrarily selected, cloned, and used in experiments to quantify the relationship between leaf ADL concentration and components of resistance to Uromyces striatus, the causal agent of alfalfa rust. Three components of resistance were quantified: infection efficiency (pustules per cm2 leaf area), latent period (the time from inoculation to when 50% of the pustules were visible), and sporulation capacity (the number of urediniospores produced per pustule). Although analysis of variance found significant differences among clones for infection efficiency, latent period, and sporulation capacity, regression analysis revealed little or no relationship between ADL concentration and components of alfalfa rust resistance. F statistics for regression equations and t statistics for slope parameters generally were not statistically significant and when these statistics were significant, coefficients of determination (r2) values indicated that ADL concentration explained only 23% or less of the variation in resistance components

Biomass production and ethanol potential from sweet sorghum

Potential feedstocks from crop-based energy production systems range from starchy and sugary tuberous crops to woody, oilseed, or herbaceous crops (including corn, sweet and grain sorghums, and several grasses). An important characteristic of biomass crops is that the ratio of energy of the biomass product be large compared to the energy used to pro­ duce the crop. Because one of the most costly inputs in the latter component is nitrogen (N) fertilizer, any evaluation of potential energy crops must emphasize N inputs. Given its high N requirement, corn is not likely to meet all future ethanol demands. Corn also is limited by the inefficient conversion of starch to etha­ nol and by environmental and conservation considerations such as suitable land use

Switchgrass Biomass Production in the Midwest USA: Harvest and Nitrogen Management

Information on optimal harvest periods and N fertilization rates for switchgrass (Panicum virgatum L.) grown as a biomass or bioenergy crop in the Midwest USA is limited. Our objectives were to determine optimum harvest periods and N rates for biomass production in the region. Established stands of \u27Cave-in-Rock\u27 switchgrass at Ames, IA, and Mead, NE, were fertilized 0, 60, 120, 180, 240, or 300 kg N ha-1. Harvest treatments were two- or one-cut treatments per year, with initial harvest starting in late June or early July (Harvest 1) and continuing at approximately 7-d intervals until the latter part of August (Harvest 7). A final eighth harvest was completed after a killing frost. Regrowth was harvested on previously harvested plots at that time. Soil samples were taken before fertilizer was applied in the spring of 1994 and again in the spring of 1996. Averaged over years, optimum biomass yields were obtained when switchgrass was harvested at the maturity stages R3 to R5 (panicle fully emerged from boot to postanthesis) and fertilized with 120 kg N ha-1. Biomass yields with these treatments averaged 10.5 to 11.2 Mg ha-1 at Mead and 11.6 to 12.6 Mg ha-1 at Ames. At this fertility level, the amount of N removed was approximately the same as the amount applied. At rates above this level, soil NO3-N concentrations increased

Animal and plant responses for steers grazing switchgrass and big bluestem pastures

Native warm-season grasses can provide large amounts of high-quality forage during the midsummer months. Maximum potential benefits depend on management of the entire cool-and warm-season grazing system. This study compared two grazing systems for the warm-season pasture component. Fall-born steers grazed pastures of \u27Cave-in-Rock\u27 switchgrass or \u27Roundtree\u27 big bluestem over three years using either continuous or rotational grazing systems. Pasture carrying time for switchgrass and bluestem pastures and steer weight gain were considerably higher for the rotational grazing program than for the continuous grazing regimen

Sustainable tree-shrub-grass buffer strips along waterways

The midwestern landscape, which formerly consisted of prairies, wetlands, and forests, is now primarily devoted to agricultural purposes. Unfortunately, the resulting large-scale agricultural production has also produced nonpoint source (NPS) pollution of water, alteration of waterways, and disruption of wildlife habitat. NPS pollution, whether by sediment, fertilizers, or pesticides, is a problem nationwide. The agricultural community has addressed this problem by increasing soil conservation efforts and improving chemical application practices. One Best Management Practice (BMP) is the use of riparian (streamside) vegetative filter strips on watersheds prone to such pollution. Most such filter strips to date consist primarily of cool-season grasses

A Survey of the State of Utah for Areas Infested with the Stem Nematode of Alfalfa

Plant nematodes belong to a large group of invertebrates known as round worms, They derive their name from the Greek word nema, meaning thread. In literature some authors refer to nematodes as nemas. In England and many parts of the United States, plant-parasitic nematodes are called eelworms. While some damage to plants results from mechanical injury, salivary secretions injected by the nematode into the plant are usually the major cause of damage. Experiments conducted in the first part of the present century have demonstrated large differences in plant growth in soil infested with nematodes and soil freed of nematodes by chemicals. Any plant subjected to nematode attack is reduced in growth. The most important nematode which attacks and retards the growth of alfalfa in Utah is the stem nematode. This parasite has been reported in most of the major alfalfa-producing counties of the state. In certain areas the nematode is prevalent to such a degree that only resistant varieties can be grown if the crop is to remain for more than two or three years. In other areas stands and yields are reduced in varying degrees. In many additional areas it is not known if the stem nematode is present, since a complete survey of the state has never been made. The objectives of this investigation were to determine the distribution of the stem nematode of alfalfa through a complete survey of the state. The physical factors of the plant and soil which may be correlated with the presence of the nematode were likewise surveyed

Renovation of established switchgrass with forage legumes

Livestock forages, especially legumes, are an integral component of sustainable agriculture. But as farms have changed from diversified, integrated crop-livestock enterprises to highly specialized, intensive cash-grain operations, perennial forages have been drastically reduced in Iowa. As livestock and pasture decrease, the risk of soil erosion and associated nutrient and pesticide runoff increases.</p