Irrigation and integrated nutrient management for sustainable sugarcane production

Abstract

Two field experiments were conducted at Sugarcane Research Station, Thiruvalla in Pathanamthitta district of Kerala state to standardise the surface methods of irrigation with and without trash mulching and to study the potential of integrated nutrient management in sugarcane for sustainable cane production. The study was carried out for a period of two years in plant crops during 1998-1999 and 1999-2000. The influence on growth, yield attributes, yield, quality, nutrient uptake and physico-chemical properties and biological properties of the soil were investigated. . In Experiment No. I viz., 'Standardisation of irrigation management in sugarcane' the methods of irrigation with and without trash mulching was investigated. The treatment comprised of 4 methods of irrigation viz., all furrow, alternate furrow, skip furrow and irrigation once in a month (farmer's practice) under mulched and unmulched situations. The results revealed that all furrow irrigation in combination with trash mulching had positively influenced all the growth-characters, yield attributes, nutrient uptake and appreciably increased the cane, sugar and jaggery yield. It was comparable with alternate furrow irrigation with trash mulching. While cane growth and sugar production was reduced in skip furrow irrigation with or without trash mulching. Trash mulching also improved physical conditions, fertility status, microbial population and enzymatic reactions in the soil. It had also shown better retention and conservation of soil moisture and reduced the soil temperature as compared to unmulched treatments. Since the combination of trash mulching with all furrow and alternate furrow irrigation had recorded comparable values for cane

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yield, B : C ratio; it could be possible to economise the use of irrigation water by . following alternate furrow irrigation with trash mulching during the formative phase of sugarcane. It was revealed that a water economy to the tune of 41 per cent was possible in alternate furrow irrigation with trash mulching as compared to all furrow with trash mulching. By mulching alone an increase of 10 per cent in cane yield was observed in alternate furrow irrigation. While in all furrow, skip furrow or irrigation once in a month the beneficial effect of mulching was not visible to such an extent as in the case of alternate furrow irrigation. Alternate furrow irrigation under trash mulching had recorded the highest WUE, energy use efficiency and energy productivity which again suggest the effective and efficient utilisation of resources with better conservation. In Experiment No. II viz., 'Integrated nutrient management in sugarcane', studies with the integrated use of organic sources like press mud, _ trash, green manuring with cowpea, Acetobacter and Azospirillum inoculation with mineral nutrition at 50, 75 and 100 per cent dose of NPK and mineral nutrition alone were carried out. The results revealed that integrated use of press mud at 5 t ha:' with mineral nutrition at 100 per cent of the recommended dose of NPK had explicitly increased the growth characters, yield attributes and uptake of nutrients producing the highest cane, sugar and jaggery yield. However, it was comparable with the conjunctive use of press mud at 5 t ha" with 75 per cent of the recommended dose of NPK. Soil inoculation of Azospirillum at 10 kg ha-! with mineral nutrition at 100 per cent or 75 per cent had also produced significant impact on growth, yield attributes, yield and quality of cane. It also increased the B:C ratio as compared to the integrated use of mineral nutrition with green manuring, Acetobacter inoculation or trash application. Application of NPK at 50 per cent of the recommended dose along with Azospirillum inoculation had shown higher B:C ratio as compared to the integration of other organics with 50 per cent of the recommended dose of NPK.

Mineral nutrition without organics even at full dose had produced lesser cane sugar and jaggery yield as compared to the integrated use of press mud, Azospirillum, green manuring or Acetobacter along with mineral nutrition at 50 per cent of the recommended dose of NPK. The conjunctive use of press mud either with 100 or 75 per cent of the recommended dose of NPK had shown comparable values for B:C ratio, energy use efficiency and energy productivity besides improving physico- chemical properties and biological properties of soil. Hence, it is possible to save 25 per cent of the recommended dose of NPK by applying press mud at 5 t ha:'. It can be concluded from the study that alternate furrow irrigation under trash mulching had resulted in substantial savings in irrigation water during the formative phase without any reduction in yield or quality. While in integrated nutrient management, it was concluded that press mud application at 5 t ha' along with mineral nutrition at 75 per cent of the recommended dose of NPK had increased the cane yield with a saving of 25 per cent of the recommended dose of NPK. Mineral nutrition alone even at its full dose recorded comparatively lesser cane yield and B:C ratio than all other combinations with organics.