Tropical fertility

J. R. Freney. 1995. Recent developments on the use of urease inhibitors in the tropics. Fertilizer Research 42 251-259. 

Direct Application Rock. Finely ground phosphate rock has had limited use as a direct-appHcation fertilizer for many years. There have been widely varying results. Direct appHcation of phosphate rock worldwide amounts to about 8% of total fertilizer phosphate used, primarily in the former Soviet Union, France, Brazil, Sri Lanka, Malaysia, and Indonesia. The agronomic effectiveness of an apatitic rock depends not only on the fineness of the grind but also strongly on the innate reactivity of the rock and the acidity of the sod performance is better on more acid sods. Probably more than half of the potentially productive tropical sods are acidic, some with pH as low as 3.5—4.5. Certain phosphate rocks may thus become increasingly important as fertilizer in those areas. The International Fertilizer Development Center at Muscle Shoals, Alabama is active in researching this field (30). 

Agbenin J.O. Zinc fractions and solubility in a tropical semi-arid soil under long-term cultivation. Bio Fertil Soils 2003 37 83-89. 

Values of a soil fertility index (SFI, Moran et al. 2000) or a soil evaluation factor (SEF, Lu et al. 2002) were calculated to quantify the intensity of the land degradation. SFI showed the applicability to measuring soil quality and to predicting succession rate of secondaiy tropical forest (Moran et al. 2000). The following equation was used to calculate SFI values (Lu et al. 2002). 

Ammonia volatilization from fertilizers is a function of the type of fertilizer, soil conditions, meteorological conditions-temperature, wind speed, precipita-tion-and fertilizer management. Table 8.6 shows the global use of nitrogenous fertilizers and the corresponding NH3 emissions based on empirical emission factors for different fertilizer types in temperate and tropical conditions (Bouwman... 

Katyal JC, Vlek PLG. 1985. Micronutrient problems in tropical Asia. Fertilizer Research 7 69-94. 

Sissingh, H.A. (1983) Estimation of plant-avail-able phosphate in tropical soils A new analytical technique. Note 235, Institute for Soil Fertility, Haren, Netherlands Skinner, H.G.W. Fitzpatrick, R.W (eds.)... 

Oxisois The predominant soils of the Tropics. Oxisois have experienced the greatest degree of mineral alteration and horizon development of any soil. The humus breakdown is rapid and the soils are usually deep and porous, Oxisois require fertilization to support continued crop production. 

Glaser, B., Lehmann, J., and Zech, W. (2002). Ameliorating physical and chemical properties of highly weathered soils in the tropics with charcoal—A review. Biol. Fertil. Soils 35, 219-230. 

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