On three locations, two growing systems have been investigated. One system with yield trails of spring barley varieties in pure stand, seed harrowing (if appropriate), and low input of nutrients (slurry), and one system with spring barley varieties as cover crop for a grass-white clover mixture, without nutrient input beside the precropping nutrient value. Data of yield, disease susceptibility, growth characteristics and quality can be found on this web page. Additional links for further results and administrative data can be found as well.

The field experiment was carried out at Kanagarian Guguk, Limapuluh Kota District, from April to December 2002. This assessment was arranged in factorial in Randomized Block Design with three replications. Variety of corn that used in cultivation were C5, C7, P10, Bisi, A4 and Bisma variety, by 2 system of land preparation (full tillage and no tillage). Soil analysis showed that pH was acid, total nitrogen was low, high P2O5, cation excange capacity (K, Ca, Mg) were low to medium. The result showed that C5 and C7 varieties better than other varieties. No tillage system was high of nutrient uptake and C5 variety was efficient in nutrient management. The result of final soil analysis showed that C/N was low, high P2O5, high cation exchange capacity of K, high CEC, and Ca and Mg were low. The yield of C5 and C7 are high compare to other varieties: 6,45 t/ha of C5 and 6,25 t/ha of C7, with R/C 1.47 of C5 and 1.31 of C7 (Rp 1,644,500 of C5 and Rp 1,094,500 of C7).

The use of yieldgard corn varieties and their isogenic counterparts treated with and without insecticide for broiler diets did not affect the performance of broilers in terms of feed consumption, body weight gain and feed efficiency. This indicates that the different corn varieties used had similar nutrient composition. Likewise, the absence of significant differences in dressing percentage (with and without giblets) and sensory evaluation indicates that the different corn varieties used had similar effects on carcass quality of broilers. Under the conditions in which this study was conducted, it can be concluded that the absence of any significant difference in the performance and carcass characteristics of broilers suggests the safety of using the different yieldgard corn varieties and their isolines treated with and without insecticides as feed for broilers. Moreover, there is no evidence to indicate that the use of different yieldgard corn varieties would alter the performance of broilers.

The weight and chemical composition of improved white and improved yellow dent maize was compared with some local floury maize varieties. The average protein content was 10.8%, 11.1% and 10.5% in improved white dent, improved yellow dent and local floury respectively. The major carbohydrate in all the varieties was starch with local floury having a slightly higher level of sugar. Improved yellow dent was significantly (P 0.05) change in the average weight of all varieties. The average weight ranged between 28.2 in improved white dent to 29.8 in improved yellow dent. The yellow dent variety will be particularly useful in improving level of micronutrient intake. The Journal of Food Technology in Africa Volume 7 No.1, 2002, pp. 27-29KEY WORDS: Nutrient composition, white dent, yellow dent, local floury maize varieties.

Manure application increased yield. Hence the study was conducted under the conditions of moderate nutrient stress and in all probability nitrogen stress. Under this condition nutrient uptakes, biomass production and grain yields did vary between Otira, Orthega, Landora, Brazil, Svani, NK96-300, Mixture 1 (Otira, Orthega, Landora) and Mixture 2 (Brazil, Svani and NK96-300). Interaction between variety and soil fertility treatments were also significant. These findings open new possibilities for selection or plant breeding for genotypes with improved capability of nutrient acquisition from soils at different soil fertility levels e.g. in organic farming. Cropping of barley varieties in mixtures seems to increase (stimulate) nutrient uptakes (N, P, S, K, Mg, Ca, Mn, Zn, Cu and Mo) and biomass production.

The influence of different levels of N and P on haulm and tuber dry matter production, and nutrient uptake of two potato varieties, Tolcha and Menagesha, were evaluated at Bako Agricultural Research Center, westrern Ethiopia, during the years 2000 and 2002. The experiment was laid out in a split plot design having three replications with the two potato varieties assigned to the main plot while three levels of N (0, 69 and 138 kg N ha-1) and four levels of P (0, 69, 138 and 207 kg P ha-1havingfactorial combination to sub-plots. Soil samples were taken from 0 to 30 cm depth before and after treatment application to determine the selected soil physic-chemical properties. Highly significant (P0.01) differences were noted for haulm and tuber dry matter between the varieties. Increasing N levels from 0 to 69 kg ha-1 significantly increased tuber dry matter on an average by 84%. On the contrary, the effect of P was non-significant (P0.05) with respect to haulm and tuber dry matter. The variety and N interaction effect significantly(P0.01) increased haulm and tuber dry matter. There were highly significant differences (P0.01) between the two potato varieties with respect to haulm and tuber nutrient uptake. Nutrient uptake of the haulm and the tuber was significantly (P0.01) enhanced due to N applications. The soil analyses showed that the soil of the soil of the experimental site was low in organic carbon and total nitrogen. The available P of the acidic Nitisols of Bako soil was estimated to b3 7.48 ppm, which is below the critical level for potato production. The soil available P accounted only 4.3% for the variation of tuber dry matter. It was noted that 69 kg N ha-1 was found to be critical for potato production on Nitisols of western Ethiopia. Further studies on phosphorus nutrition in conjunction with organic amendments to improve phosphorus use efficiency need due consideration.

Interspecific and intraspecific differences in the efficiency of utilization of soil phosphorus (P) are explained, in part, by plant morphological and physiological variations, which characterize the plant for nutrient acquisition. As part of a study on maize genotypes characterization for P-uptake and use efficiency, kinetic parameters of P uptake and root morphological characters were evaluated for six local and improved maize varieties, grown in nutrient solution. The kinetic parameters related to P influx were: maximal transport rate (Vmax), the Michaelis-Menten constant (Km), and the external concentration when net uptake is zero (Cmin). Measured root morphological characters were: root length, radius, and surface area. Shoot and root dry matter yield and the P content in these parts were also determined. Diferences among varieties were observed in the kinetic parameters Vmax and Km, root length and in root/shoot dry matter ratio. Lower Km values were better indicatives of P uptake ability of the varietes and were significantly correlated to higher dry matter production and P-efficiency index.

Enzymes in soils originate from animal, plant and microbial sources and the resulting soil biological activity includes the metabolic processes of all these organisms. The literature shows that under favourable conditions microorganisms supply most of the enzyme activity. The effect of plants on soil enzymatic activity is due to changes in organic matter content and microbial populations, but is also formed by accumulated enzymes and by continuously released extracellular and endocellular enzymes; all of which originate in the plant root. Our research studies acid phosphatase activity linked to the previous source, by which we mean cultivated plants. Evaluation was carried out on the root systems of both the chosen species and cereal varieties and also in nutrient medium on which crops were planted under conditions of changing pH and phosphorus supply. Different varieties of winter wheat, spelt, barley and rye were used and after sterilization the seeds were sown on Murashige/Skoog nutrient medium with pH 5.6, 6.2 and 6.8 and a phosphorus supply between 30-160 mg P2O5 L-1 of medium. After 10 days of cultivation the plant roots were harvested, homogenized and the acid phosphatase activity was measured. The results show that the acid phosphatase activity in the root system of various species and cereal cultivars is negatively correlated with increasing pH and available phosphorus level in the nutrient medium.

Two corn varieties predicted to differ in digestibility were harvested at 2 cutting heights (10.2 or 30.5 cm) to determine effects on the nutrient content of the resulting silage, nutrient intake, nutrient digestibility, and production of lactating cows fed such corn silage originally harvested at two-thirds milk line. Acid detergent fiber (ADF) concentration was higher and in vitro true dry matter (DM) digestibility (IVTDMD) was lower for the variety predicted to have average digestibility. An interaction was observed between variety and cutting height because of decreased ADF and increased IVTDMD for the average digestibility variety cut at 30.5 vs. 10.2 cm; no differences were observed for the higher digestibility variety at each cutting height. When silages were fed to 32 Holstein cows in a 5-wk randomized design trial, DM intake, milk yield, and milk composition were similar. There was an interaction between variety and cutting height for DM intake and total tract apparent digestibility of DM, crude protein, and neutral detergent fiber because of lower intake and digestibility for the diets containing either the high cut, average quality variety or low cut, higher quality variety. These results suggest that increasing the cutting height to 30.5 cm does not improve silage quality or improve milk yield of cows. Although the 2 varieties selected for this trial were predicted to differ in digestibility, these differences were not great enough to influence milk yield or composition of lactating cows.