Nitrogen increased soil

The extent and severity of the damage attributable to acid depositions are difficult to estimate, since impacts vary according to soil type, plant species, atmospheric conditions, insect populations, and other factors that are not well understood. Nitrates in precipitation may actually increase forest growth in areas with nitrogen-deficient soils. 

Alternative crops Biofortification Diversification Decreases erosion Increases biodiversity Increases yield Increases soil nitrogen Recycles nutrients Pest control Plant disease control (2009) Deguine et al. (2009) Dordas (2009) Etchevers et al. (2009) Kalinova (2009) Knorzer et al. (2009) Malezieux et al. (2009) Palaniappan et al. (2009) Spiertz (2009) Zuo and Zhang (2009)... 

The form of fertiliser nitrogen can affect the pH of the rhizosphere. Ammonium nitrogen has been shown to decrease the pH in the vicinity of roots of wheat whereas fertilisation with nitrate nitrogen increased the rhizosphere pH compared with the pH of the bulk soil. Differences of up to 1.2 units occurred under field conditions (Smiley, 1974). Hauter and Mengel (1988) used Sb electrodes to measure soil pH at the root surface of red clover. Lowest pH values were found at the root tips and in a sandy soil the pH at the surface of root laterals was about one unit lower than in the bulk soil. 

Once minimal mineral content of soil for optimal growth of a particular crop is achieved, no increased concentration of vitamin C is found with more fertihzation. In the case of nitrogen, increased fertilization may decrease ascorbic acid concentration. 

Table 4 shows mean values for the relative distribution of amino acids in acid hydrolyzates of humic acids and fulvic acids extracted from the same soils. These data are expressed as a-amino nitrogen of each amino acid x 100/total amino acid nitrogen. An inspection of the data in Table 4 indicates, with few minor exceptions, similarities in the amino acid composition of humic acids and fulvic acids. Acid hydrolysis appears to destroy about one-half of the amino sugars and there are losses of threonine and serine (Sowden, 1959, 1969). No corrections are made for their decomposition because the ammonia-nitrogen would then require correction, and a valid correction for it is not possible. The ammonia nitrogen increases with length of time of hydrolysis (Khan and Sowden, 1971). 

In addition to limitation and acclimation in vegetation, soil processes play an important role in ecosystem responses to the increasing inpnt of both carbon dioxide and nitrogen. Here soil characteristics, responsible for the available nntrient pools, are of great importance. Even under increasing input of nitrogen with atmospheric deposition, nutrient concentrations can be depleted by increased uptake, especially in long term period. 

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