Read on:

• A Soil Science Renaissance. Hartemink, A.E., and A. McBratney. Geoderma, 148(2):123-129. 2008.
  dx.doi.org/10.1016/j.geoderma.2008.10.006.
• Global Soil Map (GlobalSoilMap.net). Partners are ISRIC - World Soil Information, The University of Sydney, The Earth Institute at Columbia University, NRCS National Geospatial Development Center, Embrapa, National Center of Soil Research, CSIRO Land & Water, European Commission, Tropical Soil Biology and Fertility Institute and Institute of Soil Science, Chinese Academy of Sciences. The GlobalSoilMap.net project aims to make a new digital soil map of the world using state-ofthe-art and emerging technologies for soil mapping and predicting soil properties at fine resolution. This new global soil map will be supplemented by interpretation and functionality options that aim to assist better decisions in a range of global issues such as food production and hunger eradication, climate change, and environmental degradation. It is an initiative of the Digital Soil Mapping Working Group of the International Union of Soil Sciences (IUSS) and is led by academic and research centres
  in all continents. See at www.globalsoilmap.net.
• The Feeding of the Nine Billion Global Food Security for the 21^st Century. Evans, A. Chatham House Report. 2009.
  ISBN 978 1 86203 212 5.
  www.chathamhouse.org.uk.
• Do Increases in Agricultural Yield Spare Land for Nature? Ewers, R.M., J.P.W. Scharlemann, A. Balmford, and E.E. Green. Global Change Biology 15:1716-1726. 2009.
  DOI: 10.1111/j.1365-2486.2009.01849.x
  www.interscience.wiley.com
• Nutrient Imbalances in Agricultural Development. Vitousek, P.M., R. Naylor, T. Crews, M.B. David, L.E. Drinkwater, E. Holland, P.J. Johnes, J. Katzenberger, L.A. Martinelli, P.A. Matson, G. Nziguheba, D. Ojima, C.A. Palm, G.P. Robertson, P.A. Sanchez, A.R. Townsend, and F.S. Zhang. Science 19 June 2009:324(5934):1519-1520
  DOI: 10.1126/science.1170261
  www.sciencemag.org

Efficiency of Diversified Rice-Wheat Cropping Systems Including Potato, Vegetable Peas and Groundnut Crops in Trans-Gangetic Plains

Field experiment was conducted during 2000-2003 on diversified rice-wheat cropping systems involving potato, vegetable peas and groundnut, and water management treatments in rice to increase the production, economics and water use efficiency. Inclusion of potato, vegetable peas and groundnut in rice-wheat cropping system increased the production, economics and land use efficiency on an average by 95, 75 and 11 percent, respectively. Rice equivalent yield (REY) was maximum in rice/groundnut/rice(R/G/R)-potato-wheat (24.60 t/ha/yr), which was at par with rice-potato-wheat (24.27 t/ha/yr) followed by rice-vegetable peas-wheat (19.02 t/ha/yr) as against traditional rice-wheat (11.63 t/ha/yr) system. Net returns was the highest in rice-vegetable peas-wheat (Rs.67540/ha/yr) system, which was at par with R/G/R-potato-wheat (Rs.67424/ha/yr) and rice-potato-wheat (Rs.64906/ha/yr) as against rice-wheat (Rs.38159/ha/yr) system. Irrigation to rice crop at hairline cracks (HC) in soil saved about 20 percent of total water use on an average in different cropping systems compared to traditional system of irrigating rice at disappearance of ponded water (DP). Decline in available soil K ranging from 4.0 to 12.0 percent and build up of available soil P from 41.7 to 62.5 percent was recorded from initial soil test values after 3 years in different cropping systems. The apparent soil nutrient balance (gain/loss) was negative for K (243-440 kg/ha) and positive for P (57.6-151.1 kg/ha) with varying degrees in different cropping systems.

Impact of Long-Term Phosphorus and Potassium Fertilization on Alfalfa Nutritive Value-Yield Relationships

Phosphorus (P) and potassium (K) increase alfalfa (Medicago sativa L.) yield, but little information is available on how forage nutritive value is affected by P and K fertilization The objective of this study was to investigate the effect of long-term P and K fertilization on alfalfa yield-forage nutritive value relationships. A factorial experiment with four P and five K treatments was replicated four times. Beginning in 1998 and continuing through 2004, herbage samples were collected in May, June, July, and September. Samples were analyzed for crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), in vitro true dry matter disappearance (IVTDMD and acid detergent lignin (ADL) using near-infrared reflectance spectroscopy. Soils were also analyzed for P and K concentrations Concentrations of NDF, ADF, and ADL were reduced by low P and K fertility. Addition of P fertilizer increased CP concentrations, while addition of K fertilizer reduced CP concentrations. Concentrations of NDF, ADF, and ADL and dry matter yield decreased with stand age and harvest within year. The low forage dry matter yield of unfertilized alfalfa was associated with higher IVTDMD. Yield of digestible nutrients per hectare (yield x IVTDMD) was highly correlated with yield but not IVTDMD concentration. Fertilizing for high yield, despite the slight reduction in forage nutritive value, remains the most viable strategy for maximizing digestible nutrient production per hectare in alfalfa.

Spatial and Temporal Distributions in Sandy Soils with Seepage Irrigation: II. Phosphorus and Potassium

Fertilizer management, particularly of P and K, on sandy soils is crucial to maximize production and minimize environmental impact in agricultural systems. Experiments were conducted at commercial tomato (Lycopersicon esculentum Mill.) farms in southwest Florida during the 2006 spring and winter growing seasons to elucidate P and K distributions in tomato beds and to determine leaching potential under seepage irrigation. Most P was found in the top (0-10 cm) and middle (10-20 cm) soil layers at the centerline (plant row) of the soil bed, and P concentration remained relatively constant. Phosphorus in the bottom layer (20-30 cm) and bed shoulder were similar or less than preplant levels, implying that P did not likely move outside the root zone. However, P fractionation and soil P storage capacity (SPSC) of the root zone samples revealed higher risk of P loss when applied P remained more in soil solution. Most K remained in the top layer of the fertilizer band in an order of magnitude higher concentration compared with the rest of the bed, where low and constant amounts of K were found throughout the season. This result indicated that little or no K leached during this study. Seepage irrigation may have limited downward water movement in the bed, thus nutrient leaching, therefore nutrient loss through surface runoff between growing seasons could be substantial. Current Best Management Practices (BMP) for tomato fertilization should be monitored and evaluated.

High-Yielding Corn Response to Applied Phosphorus, Potassium, and Sulfur in Nebraska

Nutrient management recommendations may change as yield levels and efficiency of crop production increase. Recommendations for P, K, and S were evaluated using results from 34 irrigated corn (Zea mays L.) trials conducted in diverse situations across Nebraska. The mean yield was 14.7 Mg ha^-1 with adequate fertilizer applied. The median harvest index values were 0.52, 0.89, 0.15, and 0.56 for biomass, P, K, and S, respectively. Median grain yields were 372, 49, and 613 kg kg^-1 of aboveground plant uptake of P, K, and S, respectively. The estimated critical Bray-1 P level for corn response to 20 kg P ha^-1 was 20 mg kg^-1 when the previous crop was corn compared with 10 mg kg^-1 when corn followed soybean [Glycine max (L.) Merr.]. Soil test K was generally high with only three site-years <125 mg kg^-1. Over all trials, application of 40 kg K ha^-1 resulted in a 0.2 Mg ha^-1 mean grain yield decrease. Application of 22 kg S ha^-1 did not result in significant yield increase in any trial. Soil test results accounted for twice as much variation in nutrient uptake when soil organic matter (SOM) and pH were considered in addition to the soil test nutrient values. The results indicate a need to revise the current recommendation for P, to maintain the current K and S recommendations, and to use SOM and pH in addition to soil test nutrient values in estimating applied nutrient requirements for irrigated high yield corn production.

Mulberry Nutrient Management for Silk Production in Hubei Province of China

The silk industry is important for south China's rural economy. Leaves of mulberry (Morus spp.) are used for silkworm production. Hubei province is one of the main silk-producing provinces in China. The objectives of this research were to survey the fertilization practices in the mulberry-producing regions in the province and to determine the best nutrition-management practice for mulberry plantations. A survey and a series of field experiments with N, P, K, and micronutrients were conducted from 2001 to 2002. In addition, a silkworm-growth experiment was also conducted by feeding leaves harvested from various fertilization treatments. The results indicate that poor soil fertility and unbalanced fertilization were the main factors limiting mulberry-leaf yield and quality in Hubei province. Nitrogen fertilization of mulberry has reached a high level (454 kg ha^-1 y^-1) in Hubei province, but P- and K-fertilization rates have not been matched with N-fertilization rates as farmers are not aware of the significance of P and K. Balanced fertilization showed positive nutrient interactions with respect to mulberry yield and quality. Potassium application increased yield and quality (protein and sugar concentration) of mulberry leaves. Silkworm growth and cocoon quality were improved when silkworms were fed with the leaves derived from K-fertilized plants in comparison with those taken from control plots. Application of Mg, S, and B also significantly improved leaf sugar, essential and total amino acid concentrations, but did not increase leaf yield significantly. It is concluded that a fertilizer dose of 375 kg N ha^-1, 66 kg P ha^-1, and 125 kg K ha^-1 is suitable for the cultivation of mulberry in the Hubei province along with Mg, S, and B, wherever necessary, for the improvement of yield and quality of mulberry leaves.

Sulfur in Soils

Sulfur (S) deficiency of crops, which has been reported with increasing frequency over the past two decades on a worldwide scale, is a factor that reduces yield and affects the quality of harvested products. Especially in Western European countries, incidence of S deficiency has increasingly been reported in Brassicaceae. For this reason, more attention should be paid to the optimization of S-fertilizer application, in order to cover plant S requirements whilst minimizing environmental impacts. In soils, S exists in inorganic and organic forms. While sulfate (SO), which is a direct S source for plants, contributes up to 5% of total soil S, generally more than 95% of soil S are organically bound. Organic S is divided into sulfate ester and carbon-bonded S. Although not directly plant-available, organically bound S may potentially contribute to the S supply of plants, especially in deficiency situations. Sulfur turnover involves both biochemical and biological mineralization. Biochemical mineralization, which is the release of SO from the ester sulfate pool through enzymatic hydrolysis, is controlled by S supply, while the biological mineralization is driven by the microbial need for organic C to provide energy.

Effects of Different Potassium Fertilizers on Phytoavailability of Pb in Red Latersol and Paddy Soil

Effects of four kinds of potassium fertilizer (KH₂PO_4, K₂SO₄, KNO₃, and KCl) at five levels (K 0, 60, 140, 240, 360 mg/kg) on the Pb concentration of rape and relationship between Pb content of paddy soil and red latersol solution with the content of Pb absorpted by rape were examined in pot trial. Results showed that the Pb concentration of soil solution significantly increased with application of KNO₃, KCl, and K₂SO₄. The application of KCl (360 mg/kg) and K₂SO₄ (240 mg/kg) can increase Pb content of soil solution up to 106.9% and 97.8%, respectively. There were similar effects of three kinds of potassium on paddy soil and increased rate was lower than that of latersol soil. The main reason was that latersol soil had more inconstant charges and smaller CEC than paddy soil. However, Pb content of soil solution was significantly decreased with application rate of KH₂PO₄, moreover Pb content of rape shoot also decreased in both paddy soil and latersol, and under its highest application rate the decreased rates of Pb concentration in latersol and paddy soil were 45.0% and 63.8%, respectively, compared with the control treatment. In the second season in KH₂PO₄ treatment, there were positive correlations between Pb absorbed by shoots and roots of rape and Pb content of soil solution.