The term fertilizer refers to any substance,which supply one or more of mineral elements essential for plant growth. In other words,it is any artificial or natural material,which makes the soil fertile for profitable crop production.It is the artificially produced concentrated source of nutrients.
Significance Of Fertilizers
It plays an important role in modern crop production.They are key inputs contributing about 30% to 70% of crop production increase in crop yield.Beside increasing yield per unit area fertilizers improve nutritional and storage quantity of many crops,particularly of the grains ,fruits and vegetables this is because fertilizers increase plant resistance to certain diseases insects and weather injury.They are used in intensive farming to supplement the soil supply of essential plant nutrients.
Fertilizers available in Pakistan and their nutrient contents
Pakistan produce a large quantity of fertilizers for domestic use and their are 11 fertilizers units operating in the country ,6 in Punjab 3 in Sindh and 2 in NWFP. There are many grades of fertilizers used in Pakistan those containing more the 25% of major plant nutrients (e.g Urea ) are called high analysis. While others like ammonium sulphate,with lower amount less than 25% are known as lower analysis. Some of the important fertilizers with nutrients content are given here
Fertilizers Use efficiency
Fertilizers Use efficiency is an index of extra gain in yield by the effective utilization of fertilizers. It is the amount of increase in yield per unit weight of fertilizers nutrients.
In case of cereals fertilizers use efficiency is measured by grain nutrient ratio.Sometimes fertilizers use efficiency is also expressed in term of the recovery of liquid applied nutrients this is by plant\leaf analysis for its nutrients content.
How fertilizers use efficiency can be improved?
It can be improved by cultural practices such as use of high yielding cultivars,sowing by drill at proper time with recommended seed rate,applying the optimum fertilizer dose by drill or placement near root zone at proper time,irrigate the crop to dissolve nutrients and facilitate their uptake by the plant maintaining optimum plant density by thinning and controlling weeds,insects-pests and diseases.
Economic Use of fertilizers during application
Economic use of fertilizers includes the proper use of fertilizers material,Beside considering their merits the cost per unit of nutrients should be assessed if various sources of the same nutrient have equal merits a cheaper should be selected.After selection correct quantity of nutrients should be applied to each crop in Pakistan most farmers ignores nutrients such as P2O5 this imbalance use of N and P2O5 is one of the major factor of the low yield of crops in Pakistan The optimum recommended N:P2O5 is 1:1 to 2:1. This balanced used of nutrients can increase up to 50% yield.The time of fertilizer application is also important and it depends on type of crops,kind of nutrients and soil moisture contents.The fertilizers are usually applied at the time of sowing in case of short duration and fast growing crops such as pulses and rabi crops in barani areas which require low nitrogen dose for long duration crops nitrogen is applied in two too three splits.
Methods Of Fertilizers Application
Applying fertilizers at the proper place is as important as applying the correct amount at the right time a good method is one by which plant can uptake nutrients easily and there three methods of fertilizer application.
This method involves the surface spreading of fertilizers and its incorporation into the soil ploughing and planking.This is done at or before sowing time.Fertilizers can be spread in the field by hand or by mechanical distribution for very large farm area
In this method fertilizers is placed in bands or in rows there are two types of placement
In this case fertilizers is applied in strips or bands 5 cm to 7 cm below the rows of seed
Row Placement(side dressing)
In standing wide row crops split application of fertilizers is usually done by side dressing.This involves placing fertilizers along side of each row and mixing it in the soil by hoeing side dressing is followed by irrigation.
Placement in bands or as side dressing is preferable for phosphate fertilizers.This is because less soil is in contact with phosphate which reduces its fixation into the soil and thereby increased its availability to the plants
This involves the scattering of fertilizers by hand or air craft on the top of the standing crops the field is irrigated immediately after top dressing.This method is used for split application of fertilizers.It is particularly useful for narrow row or densly populated crops like cereals.
NOTE: In addition of these methods fertilizers can also be applied as foliar spray. But this method is not common in Pakistan because it is laborious and costly and it can only be used for experimental purpose.