Fertiliser mixtures are physical type and come in two forms. Intimatemixture of basic fertilisers like ammonium sulphate, urea, DAP, SSP and MOPin powder form is prepared as per approved grade by the state government. Inthe second case, such physical mixtures are granulated in units designed forthis purpose. Prior to 1964, only powder mixtures were made in India. Afterthat granulated mixtures have become very popular and nearly 90 per cent ofthe total quantity is now granulated. Fertiliser mixture is a time honouredbusiness which has stood the test of time and faced competition from complexfertilisers.

Fertiliser mixtures are more versatile than complex fertilisers. In factmixtures help in improving the performance of basic fertilisers. Urea,though high analysis, faces serious utilisation problem, DAP is a lop-sidedproduct with NP ratio of 1:2:5, ammonium sulphate and super phosphate have alow nutrient content and MOP is devoid of nitrogen (N) and phosphate (P).Mixtures blend all these products as per soil and crop needs and help inincreasing their utilisation. Also, cultivators get ready-made supply of allessential nutrients and do not have to do their own blending. Mixture plantsare well dispersed and can feed interior areas of five to eight districtsvery well. Most of the supply is by trucks and material reaches within 24hours in sound condition. In Maharashtra, the mixture industry enjoys statesupport and dominant share in manufacture and sale of mixtures is of thestate sector companies. This has lent a new status and dignity to thisbusiness.

Although there are many grades of fertiliser mixtures, the more popular onesare 18-18-10, 20-2-0, 15-15-15, 20-10-10 and 8-32-6. There are somespecialty mixtures with organic base which are popular in grapes, tobacco,plantations.

The most dominant mixture, 18-18-10, supplies 180 kg N, 180 P2O5 and 100 kgK2O in one tonne of material. It can be manufactured by putting together 300kg DAP, 125 kg SSP, 75 kg rock phosphate, 50 kg ammonium sulphate, 250 kgurea, 167 kg MOP and about 25 kg priller. This will supply 80 per cent ofphosphate in water soluble form, 35 per cent nitrogen in ammonical form andrest in urea form, it will supply 30 kg sulphur which is very useful formany crops, the granule size shape, lustre is enhanced due to presence of ASand SSP, output of granulation is good. This becomes ideal fertiliser forbasal application to most crops. Utilisation of urea is enhanced.

It is now necessary to further innovate and make fertiliser mixtures moreuseful. Instead of granulating, prilling should be attempted so that marketacceptability and drilling in crop lands is further enhanced. Granulatedmixtures at times show oversize of offspeck tendencies which would beavoided in prill form. It is also necessary to experiment sale of mixturesin bulk form so that bag cost is avoided. Farmers can carry material intheir own trucks, tempos, bullock carts and use it. Instead of using 25 kgfiller, the mixture can be blended with chelated zinc sulphate 25 kg whichwill make 18-18-10 mixture ideal for paddy, wheat, sugarcane crops which allneed zinc application. Occasionally 5 kg borax or 10 Kg chelated ferroussulphate can be blended with this mixture. Then it becomes completefertiliser for sugarcane which responds to boron and iron.

In Gujarat 3, 4 grades are popular and in pockets of Saurashtra,south-central Gujarat and Mehsana area these are popular fertilisers. In MPonly two plants are active and sale of mixtures has come down. The approvedgrade 18-18-10 can be very useful for paddy, wheat, sugarcane if blendedwith zinc, but the state government must encourage this and allow new unitsto come up in east and west MP, Karnataka government has started givingencouragement to mixtures, new units are coming up and well establishedMaharashtra units are becoming active in Karnataka. There is need toencourage mixtures in Rajasthan, Punjab, Uttar Pradesh, Bihar and AndhraPradesh where they can play a useful role.

There is a problem of segregation in mixtures because of which some lots donot conform to specifications. This has to be avoided by proper technicalsupervision, blending of correct quantities in a lot and proper packing.If Maharashtra's experience is any guide, the mixture business can catch onall over the country and major complex manufacturers can participate in it.Many complex fertiliser manufacturing plants are versatile. They can preparegranulated mixtures with micronutrients without sacrificing their output perday. This will help in correcting current weaknesses of our basicfertilisers and give greater crop output through more appropriate use.

In Maharashtra DAP is not a popular fertiliser for direct use and alsopowder SSSP. However, production of 0.6 million tonnes of mixture has helpedin using 1,70,000 to 1,80,000 tonnes DAP and 1,30,000 to 1,40,000 tonnespowder SSP. This model, if effectively copied in other states, will help inincreasing phosphate consumption in India. Setting up a mixture unit is notvery expensive and it can render good service in a local way.

The author is director, Rama Phosphates