3 4 Urea 1.30 1.50 – Rock phosphate 1.50 1.50 MOP 1.0 2.40 4 5 Urea 1.50 2.00 – (and above) Rock phosphate 2.00 2.00 MOP 1.50 2.50 Source: Tarmizi (2004) 2.1.8 Environmental Problems Related to Nitrogen Fertilizer Application The usage of mineral fertilizers has become essential in the agriculture production systems in order to produce a larger volume and a better quality product. However, an excessive use of fertilizers will lead to negative impacts to the environment unless they are managed properly. The unused or excess nitrate-N can pollute ground and surface water through the soil profile (leaching). Excess nitrogen will stimulate the growth of algae and cause eutrophication in lakes and reservoirs (Domagalski 2007). The high solubility in et al., fertilizer runoff may cause serious oxygen depletion and disrupt the water ecosystem. In addition, the application of nitrogen fertilizer contributes to soil acidity which leads to acidification and decreases in nutrient availability. Moreover, excessive nitrogen fertilizer application increases the birth rate and longevity of certain pests, such as aphids, and leads to pest problems in plantation. Application of nitrogen fertilizers is a major contributor of energy use and greenhouse gases (GHG). The use of nitrogen fertilizer does not only emits N2O from soil resulting from the denitrification of N inputs, but also stimulates process-based and combustion of CO2 emissions from the production of ammonia and combustion of CO2 emissions from the synthesis of N fertilizer from ammonia (Kahrl 2010). et al.,
3 – 4 Urea Rock phosphate MOP 1.30 1.50 1.0 1.50 1.50 2.40 4 – 5 (and above) Urea Rock phosphate MOP 1.50 2.00 1.50 2.00 2.00 2.50 Source: Tarmizi (2004) 2.1.8 Environmental Problems Related to Nitrogen Fertilizer Application The usage of mineral fertilizers has become essential in the agriculture production systems in order to produce a larger volume and a better quality product. However, an excessive use of fertilizers will lead to negative impacts to the environment unless they are managed properly. The unused or excess nitrate-N can pollute ground and surface water through the soil profile (leaching). Excess nitrogen will stimulate the growth of algae and cause eutrophication in lakes and reservoirs (Domagalski et al., 2007). The high solubility in fertilizer runoff may cause serious oxygen depletion and disrupt the water ecosystem. In addition, the application of nitrogen fertilizer contributes to soil acidity which leads to acidification and decreases in nutrient availability. Moreover, excessive nitrogen fertilizer application increases the birth rate and longevity of certain pests, such as aphids, and leads to pest problems in plantation. Application of nitrogen fertilizers is a major contributor of energy use and greenhouse gases (GHG). The use of nitrogen fertilizer does not only emits N2O from soil resulting from the denitrification of N inputs, but also stimulates process-based and combustion of CO2 emissions from the production of ammonia and combustion of CO2 emissions from the synthesis of N fertilizer from ammonia (Kahrl et al., 2010).