We investigated the tolerance to weed harrowing of four spring barley varieties and examined the possible interactions between varietal weed suppressive ability and two nutrient levels. Tolerance was defined as the combined effect of crop resistance (ability to resist soil covering) and crop recovery (the ability to recover in terms of yield). The weed harrowing strategy was a combination of one pre- and one post-emergence weed harrowing. In terms of yield, the four varieties responded significantly differently to weed harrowing and the response depended on nutrient level. At the lower nutrient level, weed harrowing caused an increase in yield of 4.4 hkg ha⁻¹ for a strong competitor (cv. Otira), while there was no effect on yield at the higher nutrient level. For a weaker competitor (cv. Brazil), weed harrowing caused no change in yield at the lower nutrient level, whereas yield decreased by 6.0 hkg ha⁻¹ at the higher nutrient level. There were marked differences between the weed suppressive ability of the four varieties when not harrowed, with less pronounced but significant differences when harrowed. Weed harrowing did not change the weed suppressive ability of a variety. Varieties that are tall at post-emergence harrowing and have increased density after pre-emergence harrowing, are the ones that benefit most from weed harrowing.

We investigated the tolerance to weed harrowing of four spring barley varieties and examined the possible interactions between varietal weed suppressive ability and two nutrient levels. Tolerance was defined as the combined effect of crop resistance (ability to resist soil covering) and crop recovery (the ability to recover in terms of yield). The weed harrowing strategy was a combination of one pre- and one post-emergence weed harrowing. In terms of yield, the four varieties responded significantly differently to weed harrowing and the response depended on nutrient level. At the lower nutrient level, weed harrowing caused an increase in yield of 4.4 hkg ha-1 for a strong competitor (cv. Otira), while there was no effect on yield at the higher nutrient level. For a weaker competitor (cv. Brazil), weed harrowing caused no change in yield at the lower nutrient level, whereas yield decreased by 6.0 hkg ha-1 at the higher nutrient level. There were marked differences between the weed suppressive ability of the four varieties when not harrowed, with less pronounced but significant differences when harrowed. Weed harrowing did not change the weed suppressive ability of a variety. Varieties that are tall at post-emergence harrowing and have increased density after pre-emergence harrowing, are the ones that benefit most from weed harrowing.

Cassava production in Uganda and western Kenya has been hit hard by the cassava mosaic disease (CMD) epidemic. In response, CMD resistant cassava varieties are currently released on a wide scale. The new varieties yield up to 3 times more than the local varieties. These high yield levels will put major pressure on soil nutrient stocks. Using a local variety, an average farmer will harvest about 10 t ha-1 fresh roots, thereby removing 26 kg N, 3 kg P and 19 kg K per hectare. Using a good CMD-resistant variety, the same farmer can harvest a 30 t ha-1, thereby removing 83 kg N, 10 kg P and 47 kg K per hectare. If stems are used for planting material and/or firewood, then removal increases to 216 kg of N, 22 kg of P and 102 kg of K per ha for CMD-resistant varieties. Soils in western Kenya and Uganda are predominantly Ferrasols, Acrisols and Nitisols; old weathered soils with small nutrient stocks. Without the use of fertilizers, the rapid depletion of soil nutrient stocks seems unavoidable with the new varieties. This will eventually result in yield decline of cassava and rotational crops. The question arises if traditional cropping systems are suitable for cultivating crops with high nutrient demand. However, production levels of banana, the other important food crop in Uganda, have been sustained for over half a century in several parts of the country, despite K requirements (142 kg ha-1yr-1) of good yielding bananas (25 t ha-1yr-1) being similar to that of good-yielding cassava varieties. But, in contrast to cassava fields, traditional banana fields maintain their soil fertility through large amounts of organic inputs, on the expense of annual cropped fields and grassland. Due to the position of cassava in the farming system, it is unlikely that soil management strategies in banana can be successfully adopted by cassava farmers. However, rotating the improved cassava varieties with fertilized cash crops and introducing promiscuous leguminous inter- and relay crops in cassava fields are potential management options to improve the sustainability of the system. Nonetheless, the development of K deficits will remain a serious concern. The high yield levels of the new cassava varieties have already triggered its promotion as a cash crop. Provided that there is a good (industrial) market outlet, farmers can be motivated to use targeted organic & inorganic fertilizer to prevent soil fertility depletion.

Current emphasis on writing comprehensive nutrient management plans for crop production in the mid-Atlantic region of the United States requires accurate crop nutrient removal values for vegetable crops. Therefore, studies were conducted to measure nutrient uptake in harvested fresh sweet corn (Zea mays) ears in 2003 on a sandy loam soil and in 2004 on a silt loam soil, in New Jersey. Nine varieties were included in the study to represent early, mid-, and late-season hybrids. Corn production practices followed local extension recommendations. The crop was seeded by hand and thinned to ensure a uniform within-row spacing of 9 inches and a population of 23,231 plants/acre. Nutrient concentrations were determined on ear and stover samples oven-dried at 70 degrees C for 72 hours. Mean nutrient uptake values for full-season varieties based on a typical sweet corn yield of 150 cwt/acre (about 18,396 ears/acre) would be projected to remove (in lb/acre) 51 N, 9.1 P, 34 K, 3.7 S, 2.0 Ca, 3.9 Mg, 0.024 B, 0.09 Fe, 0.044 Mn, 0.014 Cu, and 0.072 Zn. Values for N, P, and K are similar to reference values in Knott's Handbook for Vegetable Growers (4th ed.). Due to smaller ear size, nutrient removal values were generally lower for early and mid-season varieties. In 2004 only, nutrient removal by harvesting the crop residue was also determined by assuming a harvest of 23,231 plants/acre, minus the upper ear for the average full-season hybrid. This biomass was found to remove (in lb/acre) 126 N, 13.4 P, 173 K, 11.6 S, 20.6 Ca, 13.6 Mg, 0.05 B, 0.37 Fe, 0.30 Mn, 0.05 Cu, and 0.13 Zn.

Strawberry varieties were studied in 3 different growing areas of different soil- and ecological properties in Hungary. We have measured the optical spectra of the leaves together with their nutrient content and performed sensory examinations on the deep frozen and melted fruit. The 6 varieties were Elsanta, Marianna, Spadeka, Symphony, Camarosa, and Raurica. The 3 sites were Újfehértó, Pölöske, and Kecskemet. Colour of the leaves was characterised by their lightness and dominant wavelength. Under non-optimal soil and ecological conditions the varieties could be distinguished by their colour — the leaves became lighter and more yellow. The fruits did not produce the genetically determined taste if the plant can not grow in optimal circumstances — we found a negative correlation between the leaf colour in flowering time and the fruit flavour. Leaf colour measurements performed in flowering time make it possible to improve fruit quality by changing the nutrient supply between flowering and ripening.

A. Fermont et al., 'Improved cassava varieties increase the risk of soil nutrient mining: an ex-ante analysis for western Kenya and Uganda', pp.511-519, Springer, 2007

Cowpeas infested with Callosobruchus maculatus, in Zaria were analysed using standard biochemical methods. The analysis was to determine the effect of Callosobruchus maculatus on cowpeas at various stages of infestation. Four varieties "Kannanado", Local brown, "Dan Borno" and IAR-48 were used. Results show significant decrease in moisture with increase in infestation in all the varieties except for "Kannanado", this was also the case in carbohydrate content for all the varieties used (p < 0.05). The carbohydrate content ( lowest was 10.3%) for uninfested "Dan Borno" while the infested IAR-48 had the highest (12.4%) Slightly infested seed had the highest moisture content (12.0%) while uninfested cowpeas had lowest moisture (5.8%). A trend of increase in protein content with severity of infestation was observed in the varieties used, though I.A.R. 48 deviated from this pattern (p < 0.05). Uninfested "Dan Borno" had the lowest protein content (1.4 %) and IAR-48 the highest (1.7%).Lowest lipidcontentwasfound in slightlyinfested seeds ( 15.6 %) and the highest (22.6 %) for the severely infested. A significant increase in lipid and ash contents of the cowpeas with increase in severity of infestation was observed in all the varieties (p < 0.05).The damage caused by C.maculatus to all varieties of cowpea analysed did not significantly affect their nutrient composition though they attract less market value than uninfested varieties.

This study presents a review of experiments made during 20 years with the foliar diagnosis method. Leaves samples of apricot, cherry, pear and apple trees have been collected at prescribed dates on healthy and productive orchards and analysed for their N, P, K, Mg and Ca-contents. Reference values were calculated according to average contents and statistical distributions of the results. In some cases, specific reference values had to be defined for some varieties, nutrient elements or years. Any other sample can then be analysed and compared to the proper reference values; differences from reference values are interpreted in terms of nutrient availability, equilibrium in nutrient uptake and tree vigour. Results obtained so far confirm the interest of the foliar diagnosis approach; this method might be further improved by a more precise definition of sampling time and by a more elaborate evaluation of nutrient contents and ratios, as realised in the DRIS model.

The crop removal of K often equals or exceeds that of N. Under intensive cropping with high yielding varieties and imparity in nutrient use, K from soils getting depleted is evident from number of field experiments conducted across the country under the all India Coordinated Research Projects (AICRP) of the Indian Council of Agricultural Research (ICAR)......

In this research, quality properties and some nutrient contents of the important dry bean varieties grown in Sakarya and Eskisehir Locations in 2005 and 2006 seasons were analized. | Bu araştırma 2005_2006 yıllarında, Sakarya ve Eskişehir lokasyonlarında önemli kuru fasulye çeşitlerimizin kalite özelliklerinin ve bazı besin elementlerinin analiz edilerek, lokasyon farklılıklarının kalite üzerine etkilerinin araştırılması ve kaliteli çeşitlerin belirlenmesi amacıyla yapılmıştır.