Soil health and sugarcane productivity management through integrated nutrient management by using different organic manure sources and planting geometries in lateritic soils of Konkan region of Maharashtra

Introduction

Sugarcane is an old energy source crop, of industrial importance next to cotton and occupies the pivotal position in the Indian economy. If also provides livelihood to millions through an organized industry, and it accounts about 60-70% of the cost of sugar production. If also contributes about 65% of the total world sugar production. The demand for the sugar in world in increasing and it was estimated that by 2030 AD, India requires about 33 million tonnes of white sugar. But with present level of cane productively, India would not able to meet the 75% of projected requirement. Thus productivity of the soil is to be enhanced to the tune of 110 tha -1 . Soil quality holds the prime importance for productivity of long duration high biomass producing crop like sugarcane. It describes the sum total of physical, chemical and biological properties of the soil. It regulates the nutrient and moisture availability dynamics and rooting behaviour. Fortunately, the sugarcane production system mainly comprises of ratooning practice which take an advantage of saving on land preparation planting seed cost.

Thus, integrated use of various sources of organic manures along with chemical helps in improving the soil health as well as fulfil the nutrient demand of the crop and helps to sustain the sugarcane productivity on long term basis. Another as important aspect in relation to sugarcane cultivation is the planting geometry. As sugarcane being a perennial crop and put forth the dense canopy cover throughout the life period creates the problems in aeration and impedes direct solar radiation led to direct competition for the recourses. It also hinders the intercultural operations and close planted cane requires high seed rate which ultimately increases the cost of cultivation. Thus the technique of spaced planting and above that paired row planting has brought out the promising results. Soby adjusting the row distance and changing the planting geometry will enhance maximum aeration, uniform solar light distribution, efficient irrigation and inter culturing helps to maintain the productivity to a desired level. Thus keeping this views, the present investigation regarding soil health and sugarcane productivity management through integrated use of nutrients by using different sources of nutrient under different planting geometries was under taken at Agronomy form of College of Agriculture, Dapoli.

Materials and Methods

The field Experiment was conducted on plot number 60 and 63 of 'C' block of the Department of Agronomy, College of Agriculture, Dapoli. Geographically Dapoli (Dist. Ratnagiri) is located at the 17°45'57" N and 73°10'29" E in the subtropical zone. Standing at an altitude of 157.8 meters, slightly above mean sea level. The data regarding different weather parameters recorded at the meteorological observatory at department of Agronomy, College of Agriculture, Dapoli. The climate is subtropical which is characterized by warm and humid atmosphere. Over all the variations in weather parameters during both the years of investigation were not observed to considerable extent during both the years of study. The field experiment was laid out in strip plot design with two factors forming 30 treatment combinations replicated thrice. Horizontal strip consisted of six planting geometries viz., 75 cm SRP, 90 cm SRP, 60 -90 cm PRP, 60 -120 cm PRP, 60 -150 cm PRP, 75 -150 cm PRP and along vertical strips five integrated nutrient management treatments, viz., 100% RDF inorganic, 75% RDF N inorganic + 25% N organics, 50% RDF N inorganic + 50% N organics, 25% RDF N inorganic + 75% N organics and 100% N organics were allocated. The soil was also analysed for physical, chemical and biological properties. The soil analysis indicated that the soil of experimental plot was sandy clay loam in texture, moderately acidic in reaction with moderately high in organic carbon content. Soil was medium in available nitrogen), low in available phosphorus and fairly high in available potassium. The cultivar used was Co-92005 planted during February 2018 suru season and after harvesting; same was continued as ratoon during 2019 by repeating the same set of the treatments during next year. Planting of sugarcane was done to by using two budded sets after preparation of planting layout as per the treatments. Integrated nutrient management was done as per treatments by using straight fertilizers and various sources of organic manures to replace the chemical fertilizer N. Sources mainly consist of FYM 40%, poultry manure 40% and vermicompost 20%.All the crop management practices were carried out as per recommendation. Necessary plant protection measures were taken to keep the crop pest and disease free. Randomly five plants were selected for periodical growth, yield attributes and yields. Millable cane yield was estimated after cutting, removing of trash and topping of canes from each plot and weight was recorded and converted on per hectare basis (t ha -1 ). The biological analysis of soil was done to access the microbial count per gram of soil pertaining to bacteria(X10 5 cfu g -1 soil), fungi(X10 3 cfu g -1 soil)and actinomycetes (X10 5 cfu g -1 soil) by using serial dilution technology at initial soil samples as well as after harvest of both plant and ratoon cane. Similarly, to assess the physical status of soil it was analysed for bulk density and maximum water holding capacity of soil. Chemical properties of soil were known by analysing the soil for pH, EC, % organic carbon along with N, P 2 O 5 and K 2 O availability kg hectare -1 at initial and after harvest of plant cane and ratoon cane. Nutrient uptake studies were also done to assess the nutrient utilization by the crop during both the years. The data obtained is used for preparation of nutrient balance sheet to get the real picture of soil health build up during both the years of investigation.

Results and Discussion

Planting geometries

The data regarding growth parameters viz., height of plant ( cm) number of leaves per plant dry matter accumulation (g), number of internodes per cane is presented in table showed a significant influence of the planting geometries. All these parameters showed statistically higher values due to planting of cane at 60-120 cm paired row as compared to the rest of the treatments; followed by 60-150 cm PRP and 75-150 cm PRP. However, decreasing the spacing between the rows led to decline in the trend of various growth parameters. Similar trend was also observed in yield attributes like number of millable cane ha -1 , number of internodes and single cane weight which was ultimately reflected in the cane yield tha -1 . The treatment 60-120 cm PRP recorded improvement in the cane yield to the tune of 41.4%, 24.9%, 25.6%, 14.5%, and 15.9% in pooled data over 75 cm, 90 cm, 60-90 cm, 60-150 cm and 75-150xm planting spacing respectively. The increased growth and yield of cane with 60-120 cm owed due to the better air circulation, uniform distribution of light over plant canopy which might have enhanced photosynthetic efficiency. This might have increase the number of millable canes per hectare and individual cane weight which led to increased cane yield t ha -1 . Mahadevswamy, 2001, and Singh et al., 2016 [6] also recorded the similar results. Further in present investigation among paired row plantings, it was also observed reduction in yield during both years and in pooled data at wider spacingi. e. 60-150 cm and 75-150 cm PRP as compared to 60-120 cm PRP, might be due to having direct relation with increased spacing between the rows causes to cessation of competition and compensation among shoots, and formation of non-productive voids (Benda et al., 1987) [1] . Lower growth and yields in case of close spaced planted cane i.e. 75 cm, 90 cm and 60-90 cm (PRP) as compared to the wider rows might be dense population led to severe competition among the shoots reduce the single cane weight. Conclusions drawn corroborate the findings of Yadav and Singh (1986) [7] . Data regarding soil health parameters like bulk density, water holding capacity, soil microbial count, pH, EC and % organic carbon along with nutrient balance sheet after harvest of ratoon cane is presented in Table 3 and4. Data reveals that all the soil health parameters were not significantly influenced due to various planting geometries. There is also very less variation was observed in net gain / loss of nutrients from the soil due to the effect of various planting geometries after two years of investigation.

Integrated nutrient management i. Growth yield attributes and yield

Integrated application of 75% N inorganic + 25% N organic to the sugarcane recorded significantly higher number of shoots, leaf area per plant, dry matter accumulation and millable cane height as compared to rest of the treatments except 100% RDF through chemical where both these treatments were at par with each other during both the years. Further both these treatments showed their superiority over 50% N inorganic + 50% N organic followed by 25% N inorganic + 75% N organic followed by 25% N inorganic + 75% N organic and 100% N organic in that descending order of significance. Thus similar trend was also observed in the yield attributes like number of millable cane ha - 1 , number of internodes and single cane weight which was ultimately reflected in the sugarcane yield tha -1 during both the years and in pooled data analysis. The treatment 75% N inorganic + 25% N organic registered improvement in the yield to the tune of 1.8%, 22.6%, 44.6% and 66.9% over T 1 , T 3 , T 4 and T 5 respectively of pooled data of two years. This might be due to the fact that 75% N inorganic N was readily available to the crop and fulfil the initial nutrient demand and rest of 25% N through organic source insured slow and steady supply of nutrient there by maintaining nutrient availability during post tillering stage. Similar findings were also reported by Mulik, 2013 [4] .

ii. Soil physico-chemical and biological properties

The data presented in Table . 3 revealed that application of 100% N through organic source registered significantly higher bulk density gcc -1 , maximum water holding capacity (%), soil microbial population (fungi, bacteria and actinomycetes) as well soil chemical parameters like EC, pH and % organic carbon. But for each successive replacement of 25% N organic by inorganic source of N, there was observed a significant decline in the soil health parameters there by, recorded higher bulk density, lower water holding capacity, pH, % organic carbon, but increased in the electrical conductivity, indicating the deteriorations in soil health due to continuous use of chemicals in sugarcane crop during both years. It was observed the linear relationship in between the organic matter added and the physicochemical and biological properties of the soil. This might be due to the fact that due to addition of organic carbon in the soil, enhances the microbial activities in the soil, causing better soil aggregation due to the cementing action. (Kharche et al., 2013) [2] .

iii. Nutrient balance in the soil

The nutrient balance is the function of difference between initial soil nutrients + nutrient added and uptake of nutrients by crop and balance remain in the soil in available form. Data presented in Table 4 insinuates the fact that application of 100% N through organic source shows significant gain in N,P 2 O 5 and K 2 O in the soil and its trend was declined for each successive replacement of 25% N organic by inorganic source. Due to which 100% N through inorganic (T 1 ) showed net loss of nitrogen and potassium but slight gain in phosphorus after two years of experiment. The positive balance of N in organically treated plot might be due to temporary biological immobilization and continuous mineralization. (Singh et al 2010) [5] . Where as in case of P 2 O 5, application of FYM and other sources reduce the phosphate fixation and increased 'P' mineralization. The extent of availability of potassium was low or negative might be due to the fact that there was luxuriant uptake of potassium by sugarcane. (Mulik, 2011) [4] .

Interaction effect

Among the various interactions, the treatment combination 75% inorganic + 25% N organic along with planting of cane at 60-120 cm PRP (P 4 T 2 ) recorded significantly higher single cane weight (kg) and cane yield t ha -1 as compared to the rest of the treatment combinations followed by P 4 T 1 similar findings were also reported by Manimaran et al., 2009

Conclusion

It is concluded that, for maintaining higher productivity of sugarcane with sustained soil health it should be planted at 60-120 cm (PRP) and fertilized with 75% N inorganic + 25% N organic.

References

1. Benda GTA, Dunkelman JW, Irvene JE. Narrow row spacing and Sugarcane Productivity. Sugarcane. 1987;4:1519.
2. Kharche VK, Patil SR, Kulkarni AA, Patil VS, Katkar RN. Long term integrated nutrient management for enhancing soil quality and crop productivity under intensive cropping system of vertisol. J Ind Soc Soil Sci. 2013;61(4):323-332.
3. Singh KP, Srivastava TK, Suman A, Singh PN. Sugarcane productivity and soil health in a bio-nutrition based multiratooning system under sub-tropics. Ind J Agric Sci. 2010;80(8):746-748.
4. Singh SC, Yadav S, Yadav S, Yadav SK, Tiwari AK, Sharma BL. Studies on plant geometry and nutrient management strategy in relation to mechanization in sugarcane (Saccharum spp. Hybrid). Agrica. Ind J Com. 2016;5(116):118.
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6. Manimaran A, Kumar KS, Permaul K, Singh S. Hyper production of cellulase-free xylanase by Thermomyces lanuginosus SSBP on bagasse pulp and its application in biobleaching. Applied Microbiology and Biotechnology. 2009 Jan;81:887-893.