Read on:

• Continuous Cropping, Fertilization and Organic Manure Application Effects on Potassium in an Alfisol under Arid Conditions. Srinivasarao, Ch., K.P.R. Vittal, S. Kundu, P.N. Gajbhiye, and M. Vijayasankar Babu. 2010. Communications in Soil Science and Plant Analysis, 41:6, 783-796.
• Potassium-dependant Wood Formation in Poplar: Seasonal Aspects and Environmental Limitations. Ache, P., J. Fromm, and R. Hedrich. 2010. Plant Biology 12(2):259-267.
• The Miracle of the Cerrado; Brazil has revolutionised its own farms. Can it do the same for others? The Economist, 26 August 2010.
• Agriculture's Role in Greenhouse Gas Emissions and Capture. American Society of Agronomy, Crop Science Society of America, Soil Science Society of America. August 2010. www.soils.org/files/sciencepolicy/ghg-report-august-2010.pdf
• Rising Global Interest in Farmland: Can it Yield Sustainable and Equitable Benefits? The World Bank report, September 2010.
• News from International Union of Soil Sciences (IUSS). The World Reference Base for Soil Resources/WRB (the soil correlation system of the IUSS) has a new homepage at the FAO site: www.fao.org/nr/land/soils/soil/en/. It informs about all publications based on the second edition of WRB (2006). Especially important are: 1. the latest revised version (first update 2007), 2. the translations (up till now: Arabic, German, Polish, Russian, and Spanish), 3. the newsletters, 4. the "Guidelines for constructing small-scale map legends using the WRB". Originally designed for classifying pedons, with these Guidelines WRB can also be used for map legends (at least for scales 1:250 000 and smaller).

Organic Agriculture: Why so Few Farms Convert

Organic farming recorded significant growth in Switzerland, especially between 1990 and 2005, and won the support of both farmers and consumers. Despite this, organic farms are noticeably underrepresented in the arable farm regions; this situation is certainly due to the usually greater demands placed on farm conversion in these regions than in grassland. A survey of around 600 organic and PEP arable farms was conducted to determine which factors deter farmers from converting. The greatest fears expressed were the weeds pressure and the increased work needed for their control, the insufficient profitability resulting from too-low surcharges on product prices, problems in nutrient supply and the too strict or too frequently changing guidelines. The results of the organic arable farm survey show that these fears are only partially justified. Increasing neighbourly exchanges should therefore promote the expansion of organic farming.

Effect of Potassium on Growth and Yield of Soybean

The experiment was conducted at the experimental space of Botany Department, Jahangirnagar University, Savar, Dhaka during Rabi season 2004-2005 to find out the effect of potassium (K) on growth and yield of soybean. The soybean variety, G-2 (Bangladesh soybean-4) was used in this experiment as test crop. The treatments were: K_l (No application of K), K₂, K₃, K₄, K₅ and K₆ were application of 50%, 75% 100% 125% and 150%, respectively of the BARC recommended dose of K. Nitrogen, P and S were applied as blanket as per BARC recommendation. Seeds were inoculated with Bradyrhizobium inoculum before sowing. All the treatments of K application showed higher growth than that of control. Treatment K₅ (9.38 kg K ha^-1) showed maximum growth. The application of K (K₅ treatment) produced the highest seed yield (7.61 g plant^-1), which was 82.93% higher than that of control. The yield changed as a parabola curve with the increase of K application. The yield components, namely number of pods plant^-1, number seeds pod^-1, pod weight plant^-1 and number of seeds plant^-1 increased with the increase of K levels up to 9.38 kg K ha^-1. The application of K at 9.38 kg ha^-1 (which was 25% higher over BARC recommendation) produced the highest seed yield of soybean (7.61 g plant^-1). So, for better yield of soybean in silty clay loam soil of Jahangirnagar University farm, application of K should be increased to 25% higher over BARC recommendation.

Improving Nutrient Use Efficiency by Exploiting Genetic Diversity of Potato

Three separate field experiments were conducted to compare the nutrient efficiency indices, AUE (agronomic use efficiency), PUE (physiological use efficiency) and NUE (nutrient uptake efficiency) of ten Indian potato cultivars for the identification of nutrient efficient cultivars. Results showed wide variation in the nutrient efficiency of different potato cultivars.

Kufri Pukhraj was the most N, P and K efficient cultivar among ten cultivars tested in the absence as well as presence of green manure. The efficient cultivars gave higher tuber yield under N, P and K stress (i.e with less dose of N, P and K fertilizer) and had higher AUE than less efficient cultivars. Mean AUE of N of different cultivars varied between 62 and 97 kg tubers/kg N without green manure and between 68 and 100 kg tubers/kg N with green manure. Mean agronomic use efficiency of Kufri Pukhraj was 97 and 100 kg tubers per kg N without and with green manure, respectively which was significantly higher than all other cultivars The main cause of higher nitrogen efficiency in the presence of green manure was the capacity of a genotype to use/absorb more N per unit green manured soil i.e. the ability of the root system of a genotype to acquire more N from green manured soil (NUE).

Most P efficient cv. K. Pukhraj produced yield of 300 q/ha without P whereas K. Badshah and K. Ashoka needed 100 kg P₂O₅/ha to produce yield of 270 and 304 q/ha, respectively in the same field. Similarly most K efficient cv. K. Pukhraj produced yield of 364 q/ha without K whereas K. Badshah and K. Sutlej needed 80 kg K₂O/ha to produce yield of 361 and 370 q/ha, respectively in the same field. The variation in phosphorus and potassium efficiency of different potato cultivars was due to both their capability to use absorbed P and K to produce potato tubers (PUE) and to their capacity to take up more P and K per unit soil (NUE).

Integrated Nutrient Management in Potato Based Cropping Systems for Eastern Indo-Gangatic Plains of India

In order to reduce the use of fertilizers and utilize residual fertility of potato crop, different integrated nutrient management options were examined in two most popular cropping systems viz., rice-potato-onion and maize-potato-green gram of eastern plains at Central Potato Research Station, Patna during 2004-2007. Besides, different recommended dose of fertilizers and 100% organic treatments (farm yard manure to replace recommended dose of N to all crops), other treatments included reduced doses of nutrients to subsequent crops, recycling of crop residue and application of FYM. The maize-potato-green gram sequence gave higher potato yield due to improved soil physical conditions. However, the net return and potato equivalent yield (PEY) was higher in rice-potato-onion system due to higher returns from their component crops. Results indicated the possibility to economize fertilizer in green gram crop but not in onion by replacing 50% NPK through FYM or potato crop residue, when grown on residual fertility of potato. Residue incorporation of leguminous crop had more beneficial effect on subsequent maize crop but same effect of onion residue was not observed on rice. In organic treatment, potato yield was least but steadily increased over the years in both the systems. Soil physical conditions improved in second system as indicated by decreased bulk density and increased organic carbon in sub soil.

Effect of Soil Solarization on Multiplication of In-Vitro Planting Materials of Potato under Field Conditions

A field experiment was carried out at CPRS, Jalandhar to study the effect of soil solarization on weeds and productivity of micro-tuber and mini-tuber crops of 3 potato cultivars. Mean maximum soil temperature recorded under the polyethylene mulch was 53.3

Correlation and Calibration of Soil Potassium Availability with Soybean Yield and Trifoliolate Potassium

The ability of soil tests to identify nutrient-deficient soils and recommend fertilizer rates that optimize agronomic yield is essential for profitable soybean [Glycine max (L.) Merr.] production. Our objectives were to correlate relative soybean yield to Mehlich-3 and 1 mol L^-1 HNO₃

Potassium Fractions in Soils as Affected by Monocalcium Phophate, Ammonium Sulfate, and Potassium Chloride Application

Soil potassium (K) deficiency has been increasing over recent decades as a result of higher inputs of N and P fertilizers concomitant with lower inputs of K fertilizers in China; however, the effects of interactions between N, P, and K of fertilizers on K status in soils have not been thoroughly investigated for optimizing N, P, and K fertilizer use efficiency. The influence of ammonium sulfate (AS), monocalcium phosphate (MCP), and potassium chloride application on K fractions in three typical soils of China was evaluated during 90-d laboratory soil incubation. The presence of AS significantly altered the distribution of native and added K in soils, while addition of MCP did not significantly affected K equilibrium in most cases. Addition of AS significantly increased water-soluble K (WSK), decreased exchangeable K (EK) in almost all the soils except the paddy soil that contained considerable amounts of 2:1 type clay minerals with K added, retarded the formation of fixed K in the soils with K added, and suppressed the release of fixed K in the three soils without K added. These interactions might be expected to influence the K availability to plants when the soil was fertilized with AS. To improve K fertilizer use efficiency, whether combined application of AS and K was to be recommended or avoided should depend on K status of the soil, soil properties, and cropping systems.

Implications in Efficient K Fertility Management in Indian Agriculture

Recommendations of potassic fertiliser are made based on available (exchangeable + water soluble) K status of soils in different soil testing laboratories in India. However, recent studies employing a variety of measures of nonexchangeable K indicated a very substantial contribution of nonexchangeable fraction of soil K to crop K uptake. Present paper examines the information generated in the last 30 years on the status of nonexchangeable K in Indian soils, its contribution to crop K needs, categorization of Indian soils based on exchangeable and nonexchangeable K fractions and K recommendations considering both the fractions of soil K. Inclusion of nonexchangeable K in the soil testing aids in predicting immediate K needs of crop plants as well as long term K needs of intensive cropping systems. Based on published information on Indian soils, district wise maps were prepared for both exchangeable and nonexchangeable K and K deficient districts of the country were identified where K application is a must. Some maintenance dose of K is required in some districts where, exchangeable K is high but nonexchangeable K is low or medium. These maps and suggested recommendations help to prioritize the K efficient zones where K application is essential and higher possibility exists for improving the K use efficiency. Special care should be taken on K fertilisation on high K requirement crops like banana, sugarcane, potato, cotton, several cereals, tobacco, intensive fodder systems, vegetables and fruit crops. Therefore, inclusion of nonexchangeable K as a soil test in the soil testing laboratories for assessing long term K supplying capacity of Indian soils under intensive cropping systems and arriving at reliable K fertiliser recommendations is essential.