Crops can not respond to nitrogenous fertilizers in acid infertile soils.
The common ammoniated fertilizers will absorb the nitrogen as the ammonium cation and the hydrogen ion from the plant will be released acidifying the root system. The acidified condition contributes to toxicities of Manganese, Aluminum and Iron and the the nutrient availability of a broad spectrum of minerals are compromised. Ammonium of itself can be quite toxic especially in seedlings. In an acid soil the use of calcium nitrate would be a good choice. The liming to 5.7 pH can avoid toxicity issues and the resolving of nutrient deficiencies in the soil should be addressed. Many acid infertile soils are low in organic matter and the use of organic amendment can be very helpful.
In the acid soil environment Aluminum is the most common toxicity. This expresses itself as a root tip necrosis compromising the nutrient absorption.
Low soil pH locks up cations (the bases). Therefore, correcting soil pH with lime or gypsum is a must do operation in order to maximize soil ion exchange capacity. Ideally, a correction of the soil to a pH ranging from 6.2 to 6.8 will be ideal for maximum nutrients uptake by the crop. However, even minor increments of pH from high soil acidity will improve crop conditions remarkably.
As Bruno suggests a complete soil analysis is recommended in determining a nutrient plan. This should also be complemented with plant analysis.
Many acid infertile soils have very low Phosphorus availability the Phosphorus inavailabilty or fixed Phosphors can be helped by having amendment with soluble silica. Silicon determinations are useful for these conditions and are not routine in many soil laboratories.
Thanks for good information, but my view is that in acid soil bacterial population is very limited or nil and due to that ammonification and nitrification processes are limited or not carry foreward without bacteria and resulting in unavailability of nitrogen to the crops.
Ashokkumar V. Rajani you are correct in the sense that the bacterial populations are very limited in acid soils. Soil amendments like biochar, which are typically alkaline may be easily produced on-site through pyrolysis and improve soil pH for better success with cultivation of agronomic crops. Meanwhile, biochar offers stable carbon molecules to "feed" soil bacteria and aid their growth and propagation. Acceptable soil chemistry must be restored on acid soils for nitrogen uptake (but also other nutrients) to be maximized.
Professor your hunch that the nitrification a bacterial mediated process could be sensitive to pH is shown clearly. You may want to look at whether the Nitrosomonas or the Nitrobacter are the most limiting in this respect.
Bruno mentioned the benefits in the acid infertile soils of biochar. The biochar not only gives a liming effect but also improves the spaces in the soil for bacteria to inhabit. The pyrolysis of woody leaves a honey combed three dimension surface to the bacteria to take residence and be protected. The soil is a physical, chemical and biological medium and all these facets are important for optimizing the productive environment.
Paul Reed sir Wood Ash also alkaline in pH, can we use for correction in acid soil pH?
Definitely wood ash is excellent for acid infertile soil and also provides good source of potassium largely deficient in many acid soil infertile situations.
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