Nitrate leaching

The fact that is not radioactive means that it can be used safely in experiments in the field, but it also means that much patient work is needed to obtain results. The approach is demanding in terms of time, equipment, and skilled manpower, but it has made a great contribution to the understanding of the nitrate problem. The results that are outlined here are from experiments made by staff at Rothamsted, but key contributions have also come from Scotland and France. " The majority of the Rothamsted experiments involved winter wheat, but oilseed rape, potatoes, beans, and sugar beet were also grown. The soil is a factor in nitrate leaching, and three types were used, the flinty, silty clay loam at Rothamsted, a sandy loam at Woburn in Bedfordshire and a heavy sandy clay at Saxmimdham in Suffolk. 

How much does Nitrogen Fertilizer Contribute to Nitrate Leaching when Winter Wheat is Growiii We saw earlier that direct nitrate losses from nitrogen fertilizer given to winter wheat are often relatively small. We saw too that... 

The precipitated I2 is filtered off and the iodine-free filtrate returned to the nitrate-leaching cycle after neutralization of any excess acid with Na2C03. 

Zaman M, Blennerhassett JD. Effects of the different rates of urease and nitrification inhibitors on gaseous emissions of ammonia and nitrous oxide, nitrate leaching and pasture production from urine patches in an intensive grazed pasture system. Agriculture Ecosystems and Environment. 2010 136 236-246. 

Philipps, L and Stopes, C (1995) The impact of rotational practice on nitrate leaching losses in organic farming systems in the United Kingdom , Biological Agriculture and... 

Adams PL, Daniel TC, Nichols DJ, Pote DH, Scott HD (1994) Poultry Litter and Manure Contributions to Nitrate Leaching through the Vadose Zone. Soil Sci Soc Am J 58 1206-1211... 

Kirchmann H, Bergstrom L (2001) Do organic farming practices reduce nitrate leaching Comm Soil Sci Plant Anal 32 997-1028... 

Stopes C, Lord El, Phillips L, Woodward L (2002) Nitrate leaching from organic farms and conventional farms following best practice. Soil Use Manage 18 256-263... 

Thus, from the viewpoint of environmental risk assessment (critical loads) the most important exposure pathways are nitrate leaching and denitrification, which are both very sensitive to anthropogenic pollution. These links of biogeochemical nitrogen cycle should be firstly quantitatively parameterized to assessing environmental risk. 

The possibility of using nitric acid as an oxidizing agent in a leaching operation is often prohibitive because many reagents used in solvent extraction are not stable in an oxidizing solution. By the AX method, however, a nitric acid (nitrate) leach solution can be converted to a weak sulfuric acid (sulfate) solution, well suited for a solvent extraction treatment. 

In this section, we concentrate on indicators that are appropriate for evaluating the impact of different farming systems on water quality, such as nitrate leaching and pesticides. 

The most common parameters to describe the indicator nitrate leaching are ... 

N-management practices to attain environmental sustainability are expected to have both low nitrate leaching potential and low nitrate leaching rate. 

The nitrate leaching rate can be described by the N-concentration in the leaching water and the amount of leakage water. Table 4-7 shows research results indicating nitrate leaching rates with respect to a per hectare and a per output unit scale. 

Table 4-7 Nitrate leaching rates from organic farming relative to conventional...

Reference scale Compared with conventional farming the nitrate leaching rates in organic farming systems are lower similar higher Author... 

It is interesting to note that if the nitrate leaching rate is related to the output of grain and milk, organic systems tend to perform similar or even worse than conventional systems. 

The appropriate parameters to measure the potential for nitrate leaching during the non-vegetative period are the Nmm-N content in soil in autumn and the N-balance. As the latter will be the subject of Chapter 3.3.1, this section will concentrate on the impact of organic farming on the Nmm-N content in the soil. 

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