PLANT NUTRITIONS
1. Plant nutrients are essential for producing sufficient and healthy food for the world's expanding population. There are 17 essential plant nutrien.These are C, H, O, N, P, K, Ca, Mg, S, Fe, Mn, Zn, Cu, Ni, Cl, B and Mo. Except this some other elements like Al, Na, Si, Se, V and Co also known as benifical elment.
lPlant nutrients are therefore a vital component of any system of sustainable agriculture.
2. Moreover, agricultural intensification requires
Increased flows of plant nutrients to crops and higher uptake of those nutrients by crops
3. The depletion of nutrient stocks in the soil, which is occurring in many developing countries, is a major but often hidden form of land degradation. On the other hand, excessive
applications of nutrients, or inefficient management, can cause environmental problems, especially if large quantities of nutrients are lost from the soil/crop system
into water or the air.
The Guide to efficient plant nutrition management
As a follow-up, soil fertility status and the evolution of soil fertility should be evaluated and monitored by agro-ecological zone. Particular emphasis should be put on long-term trends in soil fertility so that plant nutrient depletion, wherever observed, can be countered.
Environmental impact assessments should be carried
Out regularly, especially in zones with intensive use
Of fertilizers.
These are elements that are essential for plant growth and that are taken up from the soil or from water - irrigation, flood or groundwater - or are supplied via a hydroponics medium.
- Mineral fertilizers can supply main nutrients, secondary nutrients, micronutrients or mixtures of nutrients. Straight fertilizers supply only one nutrient while complex fertilizers supply many. Compound fertilizers are produced by the blending or chemical linkage of straight fertilizers or nutrients.
Organic sources
- These nutrients are materials of organic origin, either
natural or processed. Compost consists of organic materials of animal and plant origin partially decomposed through fermentation; mineral fertilizers are sometimes added to it.
Biological nitrogen fixation
Some micro-organisms are able to convert atmospheric nitrogen to ammonia for use as their nitrogen source. The conversion is made by bacteria living either on their own in the soil or, on a considerably larger scale.
Aerial deposition
Some nutrients are supplied in small quantities to the soil surface through aerial deposition. These include nitrates in rainwater, ammonia as a gas or dissolved in rainwater, sulphur in acid rain, salts and chlorine in marine spray and calcium in the form of dust.
Soil amendments
Amendments are substances that are applied to the soil to correct a major constraint other than low nutrient content. Lime, for example, is used to remedy acidity; phosphates are used to reduce phosphorus fixation; gypsum is used to improve sodic (alkali) soils;