Nitrogen in the Soil - Essay Example

Nitrogen in the soil Name: Institution: Nitrogen Budgeting for Crops Part I Paddock history for Gunnedah, Gunnedah was chosen to be put under check since proper history of the farm was available. Two years ago in the farm, sorghum yielding as at 5t/ha at 12% content of protein. This was from 150kg/ha, urea and a long fallowed from barley. This is crucial information to know the use of the land for proper accountability and test and approximation of the content of nitrogen in the soil. Proper kept and known history of a farm helps the farmer and the researchers to know the content of the nitrogen and improve the land as per what level of different minerals it requires. Last year also the farm was used and the results were as, barley 4.25t/ha at 10% protein, from 150kg Urea. The fertiliser used in this case is urea. This is because urea is readily available and it is the proven source of nitrogen for the soils (Broughton, 1981). Although there is a necessity for crop rotation, this year the land was used with growing of barley again. This was so because the land was under research and this was necessary for research purposes. At this time the target yield was approximately 5t/ha at 10% protein. At Gunnedah, the paddock has a type of soil known as the black soil, with low-mod fertility. This is from long term cropping and mostly of the same crops from one season to the other with little N. inputs through the nitrogenous fertilizers until recently, and zero tilled. In the land, the estimated Nitrogen content that is contained in the harvested Grains is as follows N targeted is yield (t/ha) x Protein % x 1.6 (1.6 for barley) = (5.0 x 10 x 1.6) = 80 keg/ha N Secondly, the Nitrogen level that is needed in the Soil of the land and especially as it is researched and as it was calculated as follows. = 80kg N/ha x2 = 160 kg/ha N =160 kg/ha N Thirdly, how much level of Nitrogen is Available in the soil that is under investigation is as follows. A proper explanation is necessary for the calculations and it is provided below. In last year, paddock yielded barley 4.25t/ha at 10% protein, from 150kg of Urea fertilizer that was applied to the land. Therefore, there was a certain level of nitrogen that was removed from the soil during the harvest time through the grains that were harvested and also the one consumed during the growth of the plants (Nutman, 1976). Nitrogen level that was targeted is the yield (t/ha) x Protein % x 1.6 (1.6 for barley) = (4.25 x 10 x 1.6) =68 kg/ha N This is the level of nitrogen that was present in the soils at sowing time =68 kg/ha N x 2 = 136 kg/ha N From this, Subtract any fertilizer N applied to get soil N at sowing = 136 – (150 x0.46) =136-69 =67 kg/ha N The fourth note on this issue is how much of the additional Nitrogen is required to the soil that will be required to be added into the soil through fertilizers. The Nitrogen level that is needed for target yield and protein = 160 kg/ha N The estimated amount of Nitrogen that is available in the soil = 67 kg/ha N Subtract any amount of fertilizer N that was applied to get soil N at sowing = 160 kg/ha N - 67 kg/ha N applied pre-sowing =160 – 67 =93kg/ha N Equivalent to (93/0.46=202kg urea) Part 2 Influence of soil OM or soil type on mineralization rates The amount of ammonium that is in the soil and that is released into the soil through a process called mineralization and this depends on several different factors. Content of the organic matters in the soils affects the rate of mineralization in the soils. This is because what affects the soils, is what is found in the soils as the matter. The quantity of the organic nitrogen in the soil: The level of amount of the organic nitrogen that was originally present at the organic matter that determines the level of nitrogen that can be ultimately mineralized. The level of temperature that is in the soil: this is also affected by the level of temperature in the air. The optimal range that is required for mineralization to occur is between 77-95 degrees Fahrenheit (Houwers et al, 1984). Amount of oxygen in the soil: Microorganisms need some levels of oxygen and since the microorganisms are living organisms they mediate mineralization, therefore, sufficient oxygen must be available in the soil. The amount of moisture content: Ideally, water is required for mineralization to occur and this should fill 15 – 70 % of pore space for the maximum mineralization in the soil. This in addition, roughly corresponds to the field capacity. The ratio of carbon to nitrogen (C:N): This ratio is of C:N is a term which is used to describe the relative amount of total carbon put into comparison with the amount of the total nitrogen level that is present in the soil or organic matter that is in the soil. This ratio is a very crucial thing in the determination of the rate of mineralization that should occur for a given type of organic matter. In addition, since the microorganisms that live in the soil require both carbon and nitrogen for their survival, net mineralization in the soils occurs when C:N ratio is approximately less than 20:1. This means that for every two amounts of carbon, there should be just 1 part of nitrogen to the net mineralization. If a farmer is applying some organic amendments to the soil in the farm, it is crucial for the farmer to become familiar with the C:N ratio to ensure the amount of N availability. Potential N losses through de-nitrification or leaching De-nitrification is the process whereby nitrate is converted to the gases di-nitrogen or nitrous oxide and subsequently it is released directly to the atmosphere. The soil bacteria carry out this type of conversion. De-nitrification is a significant mechanism for the amount of N loss on the medium and fine textured soils. It is therefore, generally not an issue on the coarse-textured soils. This is because they mostly do not remain saturated for a great length of time. In addition to this, there are several more environmental factors that can be used to determine if de-nitrification may occur and at what extent (Bouldin et al, 1979). Nitrate. The amount of Nitrate present in the soil is necessary for de-nitrification to occur. In addition, if nitrates are not present or are in very low concentrations, de-nitrification losses will be very low. Soil water content and aeration. As pointed out living organism are very crucial for the process to occur. However, de-nitrification occurs in wet soils with low oxygen concentrations. In addition, de-nitrification increase with the length of time the soil is saturated. Standing water may result in a greater percentage of nitrates being denitrified (Broughton, 1980). Amount of Temperature. Warm temperatures are crucial. This is because; de-nitrification is known to proceed faster on the warmer soils, this is particularly when the soil temperatures are greater than around 75°F. Organic matter. De-nitrification only occurs since soil bacteria are breaking down the organic matter and this is under low oxygen conditions. The bacteria use nitrate for the biochemical process. The Soils with low soluble organic carbon only have a less potential for the process of de-nitrification than soils that have high soluble organic carbon. Therefore, the nitrate that resides in the deeper soil profile there is less organic matter that will have the greatly reduced and a minimal probability of being denitrified (Beck, Materon & International Center for Agricultural Research in the Dry Areas, 1988). Level of Soil PH. De-nitrification is extremely in the soils that have a pH that is low than 5.0. Therefore, the PH level doesn’t limit de-nitrification on most of the lands. Effect of previous crop on residual N after harvest Legumes always play a wide and crucial role in the contribution of income generation, food security and maintenance of the environment for the millions of small-scale farmers in many different parts of the world and especially sub-Saharan Africa. Legumes are always intercropped with other cereals so that they can improve land productivity through a process called soil amelioration. In crop rotation, the legumes contribute to a great diversification of the cropping systems that is used and as N2-fixing plant; the previous plant planted in a land greatly affects the soils and the level of nitrogen in the soils it can reduce the mineral N fertilizer demand (Kettering International Symposium on Nitrogen Fixation, 1980). Some of the plants are heavy consumers of nitrogen while others are just light consumers. Nitrogen is the most crucial of the nutrient elements that are required for crop production and this is especially for cereals due to grain formation. However, although some inorganic fertilizers are convenient sources of nitrogen for crop growth, its use is ultimately governed and regulated by economic and environmental considerations. Therefore, this leads to the importance of crop rotation (Postgate, 1978). References Postgate, J. R. (1978). Nitrogen fixation. London: E. Arnold. Broughton, W. (1981). Nitrogen fixation. Oxford: Clarendon Press. Kettering International Symposium on Nitrogen Fixation, Newton, W. E., & Orme-Johnson, W. H. (1980). Nitrogen fixation. Baltimore: University Park Press. Bouldin, D. R., & New York State College of Agriculture and Life Sciences. (1979). Nitrogen fixation by legumes in the tropics. Ithaca, N.Y: Dept. of Agronomy, New York State College of Agriculture and Life Sciences, Cornell University. Beck, D., Materon, L. A., & International Center for Agricultural Research in the Dry Areas. (1988). Nitrogen fixation by legumes in Mediterranean agriculture: Proceedings of a workshop on biological nitrogen fixation on Mediterranean-type agriculture, ICARDA, Syria, April 14-17, 1986. Dordrecht: M. Nijhoff. Nutman, P. S. (1976). Symbiotic nitrogen fixation in plants. Cambridge [Eng.: Cambridge University Press. Broughton, W. J. (1980). Nitrogen fixation. Oxford: Clarendon Press. FAO/IAEA Consultants' Meeting on Mutation Breeding for Improved Nitrogen Fixation in Grain Legumes, Hardarson, G., Lie, T. A., & Houwers, A. (1984). Breeding legumes for enhanced symbiotic nitrogen fixation: Proceedings. Boston, [Mass.: Nijhoff. Read More