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    Improving Modeling of Nutrient Cycles in Crop Cultivation
    (2019-12-01) Upendra Singh; Cheryl H. Porter
    Agricultural productivity depends on crops receiving adequate amounts of essential nutrients from the atmosphere, soils, and/or supplied fertilizers and manures. Through the biogeochemical cycling of nutrients, fertile soils supply the following essential nutrients to plants: nitrogen (N), phosphorus (P), potassium (K), sulfur (S), calcium (Ca), magnesium (Mg), iron (Fe), zinc (Zn), copper (Cu), manganese (Mn), boron (B), molybdenum (Mo), cobalt (Co), and nickel (Ni). Deficiency of any of these nutrients results in lower productivity. In Europe, North America, and many parts of Asia, the agricultural practice of depleting soil nutrient reserves (nutrient mining) for farming ceased several decades ago. Unfortunately, nutrient mining continues in many developing countries, particularly in Sub-Saharan Africa.
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    The DSSAT Crop Modeling Ecosystem
    (2019-12-10) Gerrit Hoogenboom; Cheryl H. Porter; Kenneth J. Boote; Vakhtang Shelia; Paul W. Wilkens; Upendra Singh; Jeffrey W. White; Senthold Asseng; Jon I. Lizaso; L Patricia Moreno; Willingthon Pavan; Richard Ogoshi; L Anthony Hunt; Gordon Y Tsuji; James W. Jones
    Traditionally, research for agricultural development and improvement is based on small plot experiments that are conducted for multiple years on a research station and, on occasion, in multiple locations. The outcomes of these experiments are then transmitted in the form of recommendations to farmers through state-wide and county-based extension services. Although this approach works well for the United States and Europe where farms are normally well managed with respect to fertilizer, irrigation inputs, and pests and diseases, in some countries funding and resource challenges make this approach less practical. In the early 1980s, the United States Agency for International Development (USAID) made a bold step to support a project that was based on systems analysis of agricultural production to address food security in developing countries.
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    The Native Shrubs Philiostigma reticulatum and Guiera senegalensis: The Unrecognized Potential to Remediate Degraded Soils and Optimize Productivity of Sahelian Agroecosystems
    (2012-01) Richard P. Dick; Modou Sène ; Mateugue Diack; Mamadou Khouma; Aminata N. Badiane ; Samba Arona Ndiaye Samba; Ibrahima Diedhiou; Abel Lufafa; Ekwe L. Dossa; F. Kizito; Sire Diedhiou; Jay Noller; Maria Dragila
    The global objective of this study was to determine the unrecognized role of shrubs as key determinants in sequestration of C, water relations, and soil degradation mitigation in semiarid climatic regimes of Senegal that are representative of much of Sub-Sahelian Africa. The results showed that shrubs are the dominant controllers of hydrology, C biomass on the landscape, microbiology, and crop productivity in agroecosystem of Senegal. The major findings were: Shrubs residues decompose rapidly enough to allow non-thermal management. Shrub residues promote crop growth but it takes 2 years of incorporation before beneficial impacts on crops were measured. Both shrubs are doing hydraulic lifting of water from wet subsoils to dry surface soils Shrubs are non-competitive with crops for water and increase water and nutrient efficiency. During periods of excess rainfall shrubs promote groundwater recharge and therefore reduce surface runoff losses. G. senegalensis had the most profound impact on yields which after fours cropping the declining yields in the absence of crops resulted in a 242% difference in yield between plots with and with out this shrub. These positive impacts occurred even in the absence of fertilizer applications
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    An Assessment of Inherent Chemical Properties of Soils for Balanced Fertilizer Recommendations for Cocoa in Ghana
    (2018-04-04) Ekwe L. Dossa; A. Arthur; W. Dogbe; Abdoulaye Mando; A. A. Afrifa; S. Acquaye
    Sustainable cocoa production in Ghana would require a shift in fertilizer recommendations from general applications to site-specific recommendations of fertilizers that account for initial fertility status and actual nutrient needs of soils on which cocoa is grown. A soil fertility survey was conducted in the major cocoa regions of Ghana covering the major benchmark soils. Two hundred and twenty four plots were sampled and composite surface soils collected and analyzed for selected fertility characteristics. The results show that most of the cocoa soils have low inherent fertility characterized by low C, N and exchange capacity. All the cocoa soils sorb P, which may limit availability of P in the soil solution. The soils generally are acidic, and soils in Western region, especially the Ferralsols, show the most acidic reaction with substantially measurable exchangeable Al. The results suggest that these differential characteristics of the surveyed soils should be considered in formulating balanced site-specific fertilizer for cocoa in Ghana.
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    Improving Fertilizer Recommendations for Cocoa in Ghana Based on Inherent Soil Fertility Characteristics
    (2018-04-04) Ekwe L. Dossa; A. Arthur; W. Dogbe; Abdoulaye Mando; D. Snoeck; A. A. Afrifa; S. Acquaye
    In Ghana, cocoa has traditionally been grown as a low input crop, which has caused soil fertility deterioration, and thus, the need to integrate fertilizer use into cocoa agricultural practices. However, fertilizers recommended to farmers are general in nature and do not account for specific crop needs and inherent soil fertility conditions. This study evaluates the use of a soil diagnosis model to determine fertilizer recommendations for cocoa based on inherent soil fertility characteristics in the cocoa growing zones of Ghana. The site-specific fertilizer formulations were tested against blanket recommendations (Asaase Wura and Cocofeed) in farmers’ settings from 2009 to 2011. The results showed that DS-formulated site-specific fertilizer performed better than all blanket fertilizers in Western soils especially on the Ferralsols which are very acidic and depleted of base cations. On the other soil conditions, the site-specific formulations were comparable to the blanket formulations. Trend analysis of cocoa response to applied fertilizer suggests that P is a major determinant of cocoa productivity and that P2O5 rates >120 kg ha−1 would be required, when justified economically, for optimal cocoa yield, while potassium could be kept at around 45 kg K2O ha−1. In view of these results, the cocoa fertilizer formulas proposed for western regions of Ghana could be revised according to the DS model recommendations by taking into consideration the optima presented above. For the other cocoa regions, the DS would not be economic and therefore, proposed formulas should keep P2O5 and K2O around the optima above-presented while compensating for nutrients exported by the crop.