Nitrogen Use Efficiency with Nitrification Inhibitors - Coursework Example

Increasing Nitrogen use Efficiency with Nitrification Inhibitors Introduction Surging food insecurity and the demand for more food production has led to an increase in the use of nitrogenous fertilisers. On the other hand, the efficiency of these fertilisers is low. The loss of the element due to plants’ inability to absorb more of the artificially applied nitrogen prompts research into ways of minimising loss and maximising efficient use. Nitrogen loss has varied impacts on the economy and the environment. Chen (2008) writes that the soil and atmospheric composition of nitrogen is comparatively high and therefore, plants are unable to adequately take up the extra volume in free air. He for instance, notes that plants can only absorb up to 41% of the total amount of nitrogen introduced to the soil by nitrogenous fertilisers. Given the low rate of assimilation, there is a growing concern over the contribution of nitrogen fertilisers to green house gasses. The nitrogen added to soils is often transformed into nitrates through chemical and biological processes that constitute nitrification. Frye (2005) notes that transformed nitrates are lost through different pathways that ultimately impact on their efficient use and on the environment. The environmental effects of this loss call for effective management practices. Research studies on nitrogen use efficiency have centred mostly on the impacts on the environment, especially water pollution and the emission of nitrous oxide, which is considered a constituent of green gases. Advances in agriculture and the dangers that nitrogen emissions pose to the entire globe has prompted research and improvements in measures aimed to contain the loss and mitigate the underlying effects. Such methods include the use of nitrification inhibitors and the application of phosphate compounds. The advances have showed varied results especially because of the diversity in the mode of action and the different processes through which nitrogen is lost. It is against this background that it is important to explore the present improvements of inhibitor applications to reduce the loss. Additionally, an evaluation of the environmental impacts of the different nitrification inhibitors is as well critical. Nitrogen losses and the environment The environmental nitrogen is lost through a number of processes. The most common process is leaching. A considerable amount of the element is lost through this process and results into undesirable environmental situations. Whereas leaching leads to the loss of the element in humid areas, soil erosion plays a leading role in the tropics. Ammonia volatilisation during urea hydrolysis contributes up to fifty percent of the amount of nitrogen lost (Frye, 2005). Lastly, the immobilization of nitrogen by fast growth of micro bacteria leads to immobilization of its inorganic forms. Nitrification and the ammonification of nitrogenous fertilisers are the leading causes of loss in applied nitrogen (Anthonisen, Loehr, Prakasam & Srinath, 1997). In order to match the plant requirements and a continuous supply at different stages of plant growth, it is paramount to regulate the supply and slow down nitrogen hydrolysis and nitrification. Water pollution remains a major concern in the application of fertilisers. The conversions of ammonia and nitrites to their intermediates have profound effects on the inhibition processes. However, waste water purification is achieved through a number of ways. It is observed that nitrifying bacteria aids in the decomposition of the applied nitrogen and has direct results on the course of water purification procedures. Among the ranging processes to transform simple sulphur urea to advanced fertilisers, the modern day agriculture applies enhanced efficiency fertilisers. The application of these fertilisers is based on the fact that the products have distinct release patterns and activity timelines that correspond to plant nutrient requirements and have low impacts on the environment. This category of fertilisers includes the controlled release fertilisers (CRF). Role of Nitrification Inhibitors Upon the application of nitrogenous fertilisers, especially urea, the amount that is not taken up by the plant is converted to nitrates, which are lost by the different processes. Consequent bacterial denitrification of the nitrate into nitrous oxide has grave effects on the environment. It is important to analyse the role of nitrification inhibitors in order to explore adequately the different inhibitors and the milestones achieved in each inhibition approach. Singh (2009) observes that when a nitrification inhibitor is added to a given soil, the bacteria (nitrosomonas) responsible for the conversion of nitrogen into nitrates are affected and thus conversion rate is reduced. Apart from the reduction of nitrogen loss, the inhibitors such as dicyanide (DCD) reduce the emission of methane. The role of the nitrification inhibitors is controlled by factors such as temperature, rate of application and the time of application. For example, it is advisable to apply NI in soil temperatures ranging around 210 C and below. Apart from reducing environmental degradation, nitrification inhibitors increase productivity. On the contrary, studies suggest that the impact of NI on crop production depends entirely on the topographical and geographical conditions of an area. Nitrification Inhibitors The effects of nitrification inhibitors have formed the basis of research questions on the efficiency of nitrogen fertilisers. Wang & Zheng (2007), posit that their application with ammonium fertilisers is considered a potent approach that decreases the emission of nitrous oxide, promotes crop yield and efficient nitrogen use. In their study, the researchers observed that the application of inhibitors resulted in significant increase in the composition of the organic nitrogen. The study confirms that nitrification inhibitors impede on ammonium ion microbial oxidation. Whereas a number of inhibitors are in use, few have gained commercial acceptance. Among these, the dicyandiamide (DCD) and 3, 4 di-methylpyrazol phosphate (DMPP) have been studied. The application of the two inhibitors with ammonia and cattle manure has demonstrated efficiency in their use to reduce not only nitrogen loss, but also increasing crop yield. Comparing the relative action of the two inhibitors, it is apparent that DMPP has effective inhibition effects on nitrous oxide emission and nitrate leaching when applied at certain rates. Research studies conducted recently on this inhibitor reveals that it is effective and it can be incorporated in granular fertilisers easily. On the other hand, studies on DCD indicate that crop yields increase in situations where fertilisers with low nitrogen content are in use. Sutter, Chen, Li, Edis & Walker (2010) observe that the DCD prevents nitrogen loss at low levels of the yield graph in regions where nitrogen is a limiting factor to growth and crop performance. Application of these inhibitors depends on their compatibility with other fertiliser contents. Phosphate fertilizers, for instance, are increasingly gaining acceptance in agriculture. The natural phosphorus content in the soil is below the required threshold. It is therefore necessary for farmers to augment this quantity with artificial phosphate based fertilisers. In such scenarios, the choice of the nitrification inhibitor should take into account the compatibility of the selected NI and the type of fertiliser. As noted earlier, the soil type and the ph are major determinants of an appropriate NI. In this light, research studies have confirmed that ammonium thiosulphate (ATS) in its solid state is able to inhibit nitrification. Unlike the DCD, DMPP AM and TU, the ATS is compatible with phosphorus based fertilisers. Further research reveal that certain inhibitors increase the plant phosphorus intake. Most scholars agree that nitrification inhibitors should be studied further. In this respect, it is possible to identify the problems associated with the application of the chemicals and the effects on the environment apart from crop yield. Maximising the efficiency of nitrogen fertilisers in farming is an appropriate method applicable to inhibit loss. The N-GUARD employs neem extracts and adequately eliminates volatility, leaching and nitrification. The method is applicable because of the fact that it enables farmers to substantially cut urea use. It also assists plants to increase nitrogen uptake and reduces the activity of bacteria responsible for breaking down ammonia into nitrates. Deterrents to Application of Nitrification Inhibitors The application of inhibitors in agriculture is limited to different parts, apart from the array of research data that ascertain their importance. On the other hand, rapid rise in fertiliser and energy prices over the years has elicited raging debates on the efficient use and appropriate ways of recycling nitrogen based fertilisers. The environmental problems associated with the continued use of the nitrification inhibitors is the first notable reason for the poor response to NI. Researchers quote other factors including the relatively inexpensive costs of using nitrogen fertilisers. This is compounded by the fact that most farmers are comfortable when applying large amounts of the fertilisers, thereby reducing the lost amount. Additionally, some of the inhibitors are volatile. Nitrapyrin, for example, is very effective but has to be incorporated in the farm due to its volatility (Sutter et al, 2010). Farmers consequently, consider using extra nitrogen fertilisers instead of spending more on tillage to save time for application. The crop yield response to inhibitors is inconsistent in most cases. Studies reveal that this response depends on the factors that influence nitrogen loss. As a result, farmers do not recognise a relationship between the nitrification inhibitors and the yield. Conclusion Nitrification is cited as the major pathway through which nitrogen is lost. This is also noted as a leading contributor to environmental degradation. When ammonium based fertilisers are applied to the soil, they are converted to nitrates, which are susceptible to denitrification and leaching. Eventually, these products poison the ground and surface waters. Autotrophic nitrification, on the other hand, results in production of nitrous oxide, which harms the ozone. It is possible to reverse these effects through inhibition of the initial stages of ammonium breakdown. It is worth noting that employing nitrification inhibitors such as DMPP and ammonium thiosulphate manage nitrogen loss adequately and effectively. The use of these inhibitors is threatened by underlying factors such as their compatibility with other fertiliser contents and plant mineral requirements. References Anthonisen, A, C., Loehr, R, C., Prakasam, B, S., Srinath, E, G. (1997). Inhibition of nitrification by Ammonia and nitrous acid. Journal of Water Pollution Control Federation.48 (5):835-836. Chen, D. (2008).Enhanced Efficiency Fertilisers for Agricultural Sustainability and Environmental Quality in Australia. The University of Melbourne, Australia. Frye, W. (2005). Nitrification inhibition for nitrogen efficiency and environment protection. International Workshop on Enhanced-Efficiency Fertilizers. Kentucky Department of Agriculture’s Office of Consumer and Environmental Protection, USA. Singh, S, N. (2009).Climate Change and Crops. Berlin: Springer Publishers. Sutter, H., Chen, D., Li, H., Edis, R., Walker, C. (2010) .Comparison of the ability of the nitrification inhibitors DCD and DMPP to reduce nitrification and N2O emissions from nitrogen fertilisers. The University of Melbourne. Trenkel, M, M. (1997). Improving FertilizerUse Efficiency. International Fertilizer Industry Association. Wang, K., Zheng, X. (2007). Effects of nitrification inhibitors (DCD and DMPP) on nitrous oxide emission, crop yield and nitrogen uptake in a wheat–maize cropping system. Journal of Environmental Sciences. 19(2007) 841–847. Wu, S., Wul, S, Wang, Z.,Chen Xian., LI Yong-Shan.(2007). Effects of a new nitrification inhibitor 3,4-dimethylpyrazole phosphate(DMPP) on nitrate and potassium leaching in two soils. Journal of Environmental Sciences. 19(2007) 841–847. . Read More