I N M
Intergrated Nutrient Management
Fertilizers used need to be of right kind depending upon the soil type. For most sugarcane soils, urea is the most important source of nitrogen; super phosphate is the best source of P and muriate of potash, of K. However, various complex fertilizers also could be used. Rock phosphate, though recommended only in acid soils, could be used under normal cane growing soils in conjunction with organic manure or phosphorous solubilizing bacteria.
Availability of farm-yard-manure (FYM) is extremely limited due to dwindling cattle population and less employment of animal power for farm operations. Therefore, in sugarcane production system, important sources are press-mud, trash, and sugar factory and distillery effluents.
The press-mud contains about 1.26% N, 3.83% phosphorus and 1.46% potassium, besides about 20-24% organic carbon and 11% calcium. It is therefore an important source of nutrients in the integrated approach. The press-mud could be cured for about a month, or enriched by microbes like Pleurotus and Trichoderma and also could be prepared into bio-earth using distillery effluent and microbial degradation. About 10-25 t/ha of press-mud can be applied for supplementing nutrients.
Use of trash
Use of Sugarcane Trash
In sugarcane fields and in the vacant spaces of the farms, lot of weed growth occurs. Upon weeding, they are thrown away. Instead, all biomass could be used for composting and thus recycled. Trash could be used for mulching and then incorporation. It could be composted by various methods and sources. A novel technique is in situ composting particularly in ratoons and also upon removal by de-trashing.
Sugarcane upon harvest leaves behind stubble and root mass to the extent of 4.5% and 12.7% of cane respectively. It is about 17.2% of the total biomass produced and serves as a source of organic matter and nutrients. An estimate indicated about 4-5 tonne of dry matter contribution to a ratoon crop by the preceding plant crop. Its contribution in terms of nutrients works out to 50 kg N, 20 kg P2O5, 20 kg K2O, 1.48 kg Na, 7.8 kg Ca, 8.12 kg Fe, 1.08 kg Mn, 0.07 kg Cu and 0.10 kg Zn per hectare.
Use of effluent waste
Use of effluent waste
Green manuring
Application of green manures
A leguminous green manure adding about 7.5 to 12.5 tonnes of green matter per hectare contributes about 10 to 30 kg N/ha. Green manure inter-cropping and in situ incorporation is an important practice in the integrated system. A preceding green manure crop could be given phosphatic fertilizer which could be utilized by the succeeding sugarcane.
Bio-fertilizers
Application of bio-fertilizers
Nutrient dosages are best decided by soil testing which would help accounting for the contribution of the soil. The balance nutrient requirement is to be met by chemical fertilizers, organic sources, bio-fertilizers, and green manures. The combination should be based on the availability of the source. At present, application of fertilizers are done without considering the contribution from other sources, even if they are applied. Though it is possible to grow sugarcane exclusively by organic means (as has been demonstrated recently at Sugarcane Breeding Institute), it would be difficult to supply all the nutrient needs by organic means since obtaining huge quantities would be difficult and may be costly. Bio-fertilizers, supplemented by other sources can improve the soil status considerably. Azospirillum and phospho-bacteria are the two important and proven bio-fertilizers at present. Gluconacetobacter is yet another N fixing microorganism being extensively studied. Azospirillum application has been demonstrated to be highly beneficial particularly under low N soils and low N application rates and could supplement about 25-35% N to sugarcane directly and can promote growth indirectly. Phospho-bacteria has been found very effective in P solubilization and can make P economy in the range of 25-50%. Recently several strains of Gluconacetobacterhave been identified at Sugarcane Breeding Institute and are being studied for their effectiveness. A suitable system could be to obtain about 50 to 75% of the applied nutrients from fertilizers and the remaining from other sources (pressmud, green manure, bio-fertilizers etc.). At Sugarcane Breeding Institute, a combination of chemical fertilizers + organic manure + bio-fertilizer to contribute 50% + 25% + 25% of the dosages, respectively has been found to be equal to growing sugarcane entirely through chemical fertilizers. There are many experimental results demonstrating the beneficial effects of organic sources.
