INFLUENCE OF TRASH TREATMENTS ON SOIL C AND N INDICES UNDER SUGARCANE PLANT-RATOON SYSTEM
Loading...
Date
2022
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Dr.RPCAU, Pusa
Abstract
Sugarcane crop generates around 8-12 t ha-1 trash. The trash an asset in sugarcane system which can be used as source of biomanure/mulching. The trash mulching regulates the rhizospheric environment and ultimately improves crop growth and yield. Nevertheless, the management of soil carbon and nitrogen is a major constraint in sugarcane based intensive system for sustaining soil health and sugarcane productivity. Thus, enhancing soil carbon and nitrogen in the sugarcane-based system has become an important concern due to declining factor productivity and nutrient availability. In view of the above facts present study was carried out at Dr. Rajendra Prasad Central Agricultural University Pusa (Bihar) during the year 2020-2022, to investigate the “Influence of Trash Treatments on Soil C and N Indices under Sugarcane Plant-Ratoon System”. The field investigation was conducted in randomised block design with eight treatments and three replications. The treatments comprised of trash mulching @10 t ha-1 either alone or activated with 25 kg N ha-1 (through urea) / farmyard manure (5t ha-1) / vermicompost (@2.5 t ha-1) / trash mulching inoculated with Trichoderma viride / Azotobacter + PSB and trash incorporated in soil with no trash control. The dose of chemical fertilizer for plant (150 N: 85 P2O5: 60 K2O kg ha-1) and ratoon (170 N: 60 P2O5: 60 K2O kg ha-1) has been applied as per recommendation in all the treatments.
The results revealed that treatments of trash mulching either treated with urea/FYM/vermicompost or inoculated with Trichoderma/Azotobacter +PSB significantly enhanced CO2 evolution in soil over control. The CO2 evolution decreased continuously with the advancement of crop growth. The fractions of total organic carbon significantly increased due to trash mulching / incorporation as compared to no trash control. The very labile (1.62 – 2.76 g kg-1), labile (1.09 – 2.17 g kg-1), less labile (1.55 – 2.21 g kg-1) and non-labile carbon (2.18-2.95 g kg-1) varied significantly after two crop cycles. The carbon fractions were in order of non-labile-C (Fraction-IV) > very labile-C (Fraction-I) > less labile-C (Fraction-III) > labile-C (Fraction-II). The mean soil organic carbon (4.53-6.93 g kg-1), total organic carbon (6.26 - 9.79 g kg-1), organic carbon stock (14.70 – 20.76 Mg ha-1), microbial biomass carbon (110.73-265.16 mg kg-1) and microbial quotient (1.77 - 2.71%) differed significantly due to trash mulching treatments either activated with organics/inoculated with microbes after harvest of ratoon. carbon pool index (1.00-1.57) and carbon management index (138.36-238.30) varied and improved significantly in trash treated plots as compared to no trash control after ratoon. However, the soil carbon lability index was found non-significant.
The maximum nitrate-N fraction observed in trash mulching treatment treated with urea, while other forms of nitrogen fractions dominated in trash mulching treatments activated with organics/microbial inoculants. The N-fractions viz. nitrate-N (15.70-18.03 mg kg-1), exchangeable ammonical-N (66.46-100.50 mg kg-1), total hydrolysable-N (242.92-363.95 mg kg-1), non-hydrolysable-N (140.55-200.69 mg kg-1) and total-N (447.76-699.01 mg kg-1) differed and found significant due to treatments of trash mulching. Among the hydrolysable-N, the highest value recorded for amino acid-N followed by ammonium-N, unidentified-N and least value for hexoseamine-N. The N-indices viz. nitrogen lability, nitrogen lability index and nitrogen pool index of soil significantly influenced by trash treatments while nitrogen management index did not differ. The nitrogen fractions were in a dynamic state of equilibrium and various nitrogen fractions behaving interchangeably, as indicated by the correlation coefficient (r value) among the nitrogen fractions.
The trash mulching brings significant changes and enhancement in physical, chemical and biological environment of soil. The mean soil penetration resistance of surface (1.26 – 1.40 MPa) and sub-surface (3.68-4.09 MPa) varied significantly after harvest of ratoon crop. The significant improvement in bulk density, aggregate size distribution, pore space and water holding capacity of soil also observed in trash
mulching treatments after two crop cycles. The availabilityof macro (N, P & K) and micro nutrients (Fe, Zn, Cu & Mn) enhanced significantly with positive balance of NPK due to trash mulching.
The results revealed that plant height, dry matter, tiller, millable cane and cane length enhanced in plant and ratoon crop due to treatments of trash mulching. The mean cane yield of plant (65.96-83.31 t ha-1) and ratoon crop (54.20-71.99 t ha-1) differed significantly among treatments. Juice quality parameters viz., pol, purity coefficient and commercial cane sugar remains unaffected due to trash mulching. However, brix (%) improved significantly in ratoon crop only. The mean sugar yield varied significantly in plant (7.22-9.97 t ha-1) and ratoon crop (5.78-8.58 t ha-1) due to various trash mulching treatments. The higher sugar yield was recorded in plant crop as compared to ratoon crop. The positive relationship was found among cane and sugar yield with carbon and nitrogen indices.
The increasing cane yield resulted more uptake of nutrients by plant and ratoon crop. The mean uptake of N (230.07-297.39 Kg ha-1), P (17.22-22.07 Kg ha-1), K (205.00-283.06 Kg ha-1), Fe (3663-5505 g ha-1), Zn (712-939 g ha-1), Cu ( 1417-1835 g ha-1), Mn (723-956 g ha-1) by plant crop and N (213.47-282.40 Kg ha-1), P (15.21-20.57 Kg ha-), K (163.55-246.34 Kg ha-1), Fe (3154-4963 g ha-1), Zn (646-841 g ha-1), Mn (1253-1739 g ha-1) and Cu (621-861 g ha-1) by ratoon crop varied significantly and increased due to mulching of trash. The mean B: C ratio for plant (1.51-1.89) and ratoon (1.71 – 2.20) varied significantly. The trash mulching treatment inoculated with Trichoderma viride recorded highest B: C ratio in plant (1.89) and ratoon (2.20) crop. In general, the higher B:C ratio was obtained in ratoon crop as compared to plant crop.
The soil carbon pool parameters, soil carbon stock and nitrogen fractions get better with improvement in carbon and nitrogen indices due to trash mulching treatments. The trash mulching treatments either activated with urea/FYM/vermicompost or inoculated with Trichoderma /Azotobacter + PSB brings significant enhancement in quality of soil and productivity of sugarcane plant-ratoon system in sub-tropics. Based on B: C ratio trash mulching (10 t ha-1) treated with Trichoderma viride (500 g t-1 of trash) along with RDF produced maximum profitable cane and sugar yield in Calcareous soil.