by Raymond P Poincelot
page 1-2
by Raymond P Poincelot
page 3-4
by H V Eck and B A Stewart
page 5-20
The objective of this study was to determine the effects of long-term (1950s to 1992) cropping by farmers, using their own cultural and fertilization practices, on soil quality as measured by soil OC, total N, NaHCO3-extractable P, and pH. We sampled farmers fields at 27 Oklahoma sites (representing six soil associations) in the 1950s and again in 1992. We also sampled soil at 2 sites with native sod to determine changes in soil properties since initial cultivation. Most of the sites were in areas commonly cropped to continuous wheat (Triticum aestivum L.). One of the 27 sites was planted to tall fescue (Festuca arundinacea Schreb), in the late 1970s. on the 26 cropped sites OC and total N levels did not change significantly during the time period. Sodium bicarbonate extractable P increased significantly on 2 soil associations but remained unchanged on the other associations. Soil pH decreased on 2 associations and remained unchanged on the others. These results indicate that, except for reducing pH on some soils, farmers are growing continuous wheat without degrading these measures of soil quality.
In the study of changes (0-13 cm) OC in 25 yr and 59% in 92 yr of cultivation. Respective losses in total N were 23 and 59% in 92 yr of cultivation. Respective losses in total N were 23 and 46%. Kirkland silt loam surface (1-15 cm) soil had lost 42 and 47% of its initial OC after 58 and 92 yr in cultivation. Respective losses of total N were 29 and 36%. After cropping, both OC and total N levels in surface soils were similar to those in the subsoils. This was also true on the 26 cropped soils.
At the site converted to grassland, OC and total N increased sharply, extractable P was unchanged, and pH was increased, probably as a result of lime application. Results obtained on this site may be indicative of changes occurring on land in the Conservation Reserve Program (CRP).
by M A Jabbar, BUBL M Swallow, G D M d'Iteren and A A Busari
page 21-47
World agriculture is based on a small number of animal species and a decreasing number of breeds within each species. Several breeds of West African shorthorn cattle (Bos taurus brachyceros) are not at high risk of extinction due to interbreeding. The West African shorthorn breeds are particularly important resources because of their superior abilities to resist diseases, particularly trypanosmosis, and be productive under high humidity, heat stress, water restriction and with poor quality feed. A study was undertaken in the derived savanna area of southwest Nigeria to determine the prospects for conservation through use and possible improvement of the Muturu, a West African shorthorn breed known to be in decline throughout southern Nigeria. An analysis of farmers' breeding practices and breed preferences confirmed a strong trend away from Muturu and identified the traits farmers find least desirable about the Muturu relative to other breeds. An analysis of cattle market prices found small, but significant, price differences by bred. The best hopes for increased utilization likely in other areas of West Africa, such as southeast Nigeria, where the Muturu is better suited to the farming systems and there is a large market for this breed.
by V R Kanneganti, R P Walgenbach and L J Massingill
page 49-66
Sustainable use of mixed species pastures under management intensive rotational grazing requires information on forage dry matter availability on a daily basis for feed budgeting purposes. Forage availability, forage nutritive quality, and species composition were measured during May to September in 1994 and 1995. Forage available for daily consumption declined in both years as the season progressed. However, the magnitude of this decline was attributed to differences in soil moisture availability. Under adequate moisture conditions observed in 1994, forage was available at an average rate of 70, 68, 51, 66, 24, and 11 kg dry matter ha-1 d-1 during May, June, July, August, September, and October, respectively. Due to extended periods of dry weather in the summer of 1995, forage availability during the months of July, August and September was reduced to 26, 47, and 11 kg ha-1 d-1, respectively, Total forage consumed during 1994 and 1995 was 8580 and 6460 kg dry matter ha-1, respectively. Averaged over the two years, forage dry matter consumed during the grazing season contained 22% crude protein (CP), 45% neutral fiber (NDF) detergent fiber (NDF), and 24% acid detergent fiber (ADF). Averaged over the two years, forage cut at ground level was composed of 22% Kentucky Bluegrass (Poa pratnesis L.), 33% of mostly smooth bromegrass (Bromus inermis Leyss.) and quackgrass (Elytrigia repens (L.) Nevski), 13 % legumes (mostly white colver, Trifolium repens L.), 27% dead matter, and 5% of all other species. These fractions remained stable during the season, except under intense drought when dead matter increased as the bluegrass and white clover fractions declined. However, bluegrass and clover recovered quickly upon return of favorable moisture conditions. The results indicate that these pastures can provide significant amounts of forage under management intensive rotational grazing, but additional feed may be needed for a month or two under extended periods of water stress. While more years of data are needed to accurately assess the effects of rotational grazing on species composition, the limited set of data presented suggests that the pasture composition, a measure of pasture persistence, may remain fairly stable from year to year under the system of grazing management imposed, even though significant but transient changes were observed within a grazing season.
by J du Toit, E Joubert and T J Britz
page 67-84
Cyclopia species are used to manufacture a herbal infusion called honeybush tea. The pleasant sweet, honey-like flavour and anecdotal evidence of the beneficial qualities of honeybush tea consumption make this herbal infusion a healthy alternative to coffee and black tea. Honeybush tea has been known to South Africans for centuries and, until recently, was processed only on a small-scale, mainly for home consumption. Growing interest in herbal teas, both locally and overseas, has resulted in a revival of the honeybush teas industry. Research addressed the lack of a standardized processing method, which in turn lead to the production of poor and inconsistent quality tea.
by Steven J Guldan, Tammy May, Charles A Martin and Robert L Steiner
page 85-97
This study evaluates the forage yield and quality of legumes interseeded into sweet corn. Five legumes ('Madison' hairy vetch, 'Parabinga' barrel medic, 'Nitro' alfalfa, 'Indianhead' black lentil, and 'Arlington' red clover) were interseeded into sweet corn at last cultivation of the sweet corn in 1993 and 1994. Our objectives were to evaluate these legumes in terms of fall and spring dry-matter yield (DMY), crude protein concentration (CPC), crude protein yield (CPY), and in vitro dry matter disappearance (IVDMD). Corn ears and stover were harvested 31 August to 2 Septmeber 1993 and 16-17 August 1994. Crude protein concentration was generally higher for hairy vetch and alfalfa. Crude protein yield significantly increased from October to November in both years. November CPY was generally higher for barrel medic and hairy vetch. In April of both years, hairy vetch had the highest CPY among the overwintering legumes (hairy vetch, alfalfa, and red clover). Except for hairy vetch and red clover in trial year 2, mean IVDMD values were highest for the November sample dates.
by Janet Riley and C J Alexander
page 99-117
The concept of research impact is defined. Methods currently in use for impact assessment of projects on sustainable development are reviewed as well as those used in different fields of research. The choice of appropriate indicators of research achievement is discussed and properties of quantitative and qualitative indicators are assessed. A detailed discussion is included of current research on indicators in many research fields such as health, economics, industry, education, politics, medicine, social development, ecology, and general environmental sustainability.
It is proposed that research impact assessment involves a longterm management approach based on proper project design incorporating an impact assessment component and that the generated information requires skillful summary to determine impact in an unbiased way. While management issues have been addressed to some extent, the issues of data quality and summary have received inadequate attention. A method is proposed for collection of core indicators for monitoring and evaluation within a time period and locality beyond the immediate project zone. The resultant data set will be large and multidisciplinary; technical methods for its summary are discussed.
by Thomas A Lyson
page 119-130
Agricultural sustainability is challenging 'conventional' or 'mainstream' agriculture as the dominant organizing paradigm for teaching research, and outreach in American land grant universities. However, not all faculty members subscribe to the tenets of sustainable agriculture. This paper examines how a sample of faculty members from all land grant universities in the U.S. view sustainable agriculture. Results show that, in the minds of agricultural academics, agricultural sustainability is closely aligned with enhancing environmental quality. It is less closely tied, for the, to increasing profitability for farmers or with improving the quality of life in rural areas. Results vary be academic discipline and be personal background characteristics.
by M A Arshad, K S Gill and R C Izaurralde
page 131-154
Rising production costs, unstable cereal grain prices, soil degradation due to excessive tillage and nitrate leaching are main constraints to sustainable agriculture in the Canadian prairies. Replacing conventional tillage (CT) with no-till (NT) and cereal-fallow rotations with crop rotations comprising cereals, oilseeds and legumes is thus encouraged, but information on crop rotation by tillage interaction is scarce. Properties of a silt loam (Dark Gray Luvisol), weed population and wheat production (Triticum aestivum L.) in canola (Brassica camestris L.)- wheat-wheat (C), fallow-wheat-wheat (F), field pea (pisum sativum L.)-wheat-wheat (P) and continuous wheat (W) cropping systems were compared under CT and NT. Percentage of water stable aggregates (WSA) was reduced after a fallow season. Soil NO3-N was similar among cropped plots which was significantly lower than fallow plots in two of the three years. Ammonium-N, extractable P and penetration resistance (PR) of soil was not affected by crop rotation. The W plots tended to have more weeds than both the first (W1) and second (W2) year wheat plots in rotations. Wheat appeared to suppress weeds better than canola, field pea or fallow. Average production of 3.95 Mg ha-1 yr-1 as grain and 10.7 Mg ha-1 yr-1 as above-ground dry matter (AGDM) by the W1 were significantly greater than the corresponding production by W2 and W. Wheat grain and AGDM production in the two years of C, F, P and Q systems were not significantly different in most cases. However, cumulative yields by C, P and W systems for three years of rotation were greater than the corresponding grain and AGDM yields from F rotation by 1.10 to 4.19 and 4.3 to 8.7 Mg ha-1, respectively. Tillage did not affect NO3-N, NH4-N, O and WAS in soil but reduced its PR. The NT system provided better control of annual broadleaf weeds whereas perennial weeds were better controlled by CT. The CT system produced more grains (average of 0.42 Mg ha-1 yr-1) than NT system. Crop rotation by tillage interaction were not significant which indicated that the crop rotations were equally effective under both the tillage systems. Benefits of crop rotation over monoculture in this study were of similar nature as in earlier studies conducted on filed already under annual cropping systems. Canola and field pea were more beneficial than wheat as previous-crop for wheat production. Replacing fallow with a crop resulted in (a) increased crop production and straw returned to soil; (b) reduced potential for leaching of NO3-N; and (c) improved water stable aggregation for soil.
Transcribed by Kirsty A Smith
22 July 1998