Notes on Integrated Organic, Biofertilizer, and Inorganic Fertilizer Effects in Sugarcane Plant–Ratoon System

Integrated nutrient management in sugarcane plant–ratoon system under calcareous soil

• Source: Sinha et al., 2024, Journal of Scientific Research and Reports (JSRR), Volume 30, Issue 5, pp. 193–206

• Context: Indo-Gangetic Plains of India; calcareous soil; sugarcane produced in plant–ratoon system

• Objective: Evaluate integrated use of organic manure, biofertilizers, and inorganic fertilizer on soil properties, yield, quality, uptake, microbial population, and enzyme activities

• Experimental site: Research Farm, Dr. Rajendra Prasad Central Agricultural University, Pusa, Bihar (eastern India)

• Study area characteristics:

  • Climate: subtropical; rainfall ~1000 mm; warm, dry ripening phase
  • Soil: Entisols (Fluvents), Typic Ustifluvent; calcareous with free CaCO3 ~34%; sandy loam texture; initial pH 8.25 (1:2.5 soil:water), EC 0.29 dS/m; bulk density 1.39 Mg m^-3; SOM low; initial available N 228 kg/ha, P2O5 22.2 kg/ha, K2O 112.1 kg/ha; organic carbon 4.5 g/kg; CaCO3 ~31.63%

• Crop and duration: sugarcane cv. B.O.154; three-year trial (main plant crop + two ratoons)

• Treatments: randomized block design with 9 treatments and 3 replications; plot size 9.24 m × 5.40 m

• RDF (recommended dose of fertilizer) details:

  • Main plant crop RDF: N:P{2}O{5}:K_{2}O = 150:85:60 kg ha^-1
  • Ratoon crop RDF: N:P{2}O{5}:K_{2}O = 170:50:60 kg ha^-1

• Treatments (T1–T9):

  • T1: RDF for main plant + RDF for ratoon (as above)
  • T2: 100% NPK + Acetobacter
  • T3: 100% NPK + PSB
  • T4: 100% NPK + Bio-Compost (@ 5 t ha^-1)
  • T5: 100% NPK + Acetobacter + PSB + Bio-Compost (5 t ha^-1)
  • T6: 75% NPK + Acetobacter
  • T7: 75% NPK + PSB
  • T8: 75% NPK + Bio-Compost (@ 7.5 t ha^-1)
  • T9: 75% NPK + Acetobacter + PSB + Bio-Compost (@ 7.5 t ha^-1)

• Biofertilizers and organic inputs used:

  • Acetobacter (106 cells/mL) – N-fixer endophyte; PSB (106 cells/mL)
  • Trichoderma (10^6 cells/mL) applied to all treatments except control
  • Bio-Compost: characterized as 36% C, 1.53% N, 1.50% P, 3.10% K; micronutrients Zn 102.3 mg kg^-1, Mn 19.64 mg kg^-1, Cu 11.5 mg kg^-1, Fe 46 mg kg^-1

• Application details:

  • Half of N and all K applied at planting; remaining N top-dressed at earthing up
  • Bio-Compost applied in furrow, lightly covered and irrigated

• Growth and yield measurements:

  • Cane height, girth, and yield recorded at harvest; cane yield converted to t ha^-1
  • Juice quality: Brix, pol, and CCS% measured from composite juice; CCS% calculated via Winter’s formula; sugar yield (t ha^-1) = cane yield (t ha^-1) × CCS%

• Soil and plant analyses:

  • Soil pH, EC, organic carbon (Walkley–Black method), available N (alkaline permanganate), P (Olsen), K (flame photometry)
  • Plant N, P, K content and uptake by Microkjeldahl, molybdovandate phosphoric acid method, and flame photometry, respectively

• Microbial and enzyme analyses:

  • Rhizospheric microbial populations (bacteria, fungi, Actinomycetes, Acetobacter) by plate-count methods on selective media; dilutions 10^-2 to 10^-6
  • Enzyme activities: β-glucosidase (PNG substrate), urease (NH3-N formation from urea), acid phosphatase (p-NPP), dehydrogenase (TTC reduction)

• Key equations and indicators:

  • Sugar yield from CCS and cane yield: ext{Sugar yield (t ha^{-1})} = ext{Cane yield (t ha^{-1})} imes ext{CCS}( ext{percent})
  • RDF reduction: treatments T6–T9 used 25% reduced NPK dose relative to 100% RDF
  • Nutrient uptake and distribution were analyzed for Plant and Ratoon separately; micro-nutrients reported as mg kg^-1 in soils and as counts in microbial assays

• Summary of core findings

  • NMC, cane yield, and sugar yield were significantly affected by integrated nutrient management
  • The highest performance in the plant crop was with T9: 75% RDF + Acetobacter + PSB + Bio-Compost (7.5 t ha^-1) yielding NMC = 103.0 imes 10^{3} ext{ ha}^{-1}, cane yield = 85.8 ext{ t ha}^{-1}, and sugar yield = 11.21 ext{ t ha}^{-1}
  • Residual (ratoon) effects of T9 were also strongest: NMC = 92.4 imes 10^{3} ext{ ha}^{-1}, yield = 79.6 ext{ t ha}^{-1}, sugar yield = 9.36 ext{ t ha}^{-1}
  • Bio-compost strongly boosted overall performance; biofertilizers amplified inorganic fertilizer effects, especially when used with organic inputs
  • Control (T1) showed comparatively poor performance in NMC, yield, CCS and soil health indicators
  • Nutrient uptake mirrored yield trends: T9 registered the highest uptake of major nutrients (N, P, K) in both plant and ratoon; micro-nutrient uptake also favored T9
  • Soil fertility improvements under organics + biofertilizers + inorganic fertilizer included higher organic carbon, available N, P, K, and micro-nutrients; pH tended to decrease (from alkaline to less alkaline) and EC tended to rise with bio-compost application
  • Post-harvest soil: pH declined and EC increased in bio-compost plots; bulk density decreased (max reduction in T9 to 1.32 g cm^-3)
  • Microbial populations: bacteria, fungi, Actinomycetes, and Acetobacter all increased under organic inputs and biofertilizers; highest counts in T9: bacteria 42.8×10^6 g^-1, fungi 29.3×10^4 g^-1, Actinomycetes 28.7×10^2 g^-1, Acetobacter 34.8×10^6 ml^-1
  • Soil enzyme activities: β-glucosidase, urease, acid phosphatase, and dehydrogenase activities were highest under T9, correlating with higher soil organic carbon and microbial activity; Trichoderma presence aided decomposition

• Detailed results by parameter

  • NMC, yield, and sugar yield (Table 1, pooled over two years for ratoon):
  • T9 (75% RDF + Acetobacter + PSB + Bio-Compost @ 7.5 t ha^-1) yielded the maximum plant NMC = 103.0 imes 10^{3} ext{ ha}^{-1}, plant cane yield = 85.8 ext{ t ha}^{-1}, and plant sugar yield = 11.21 ext{ t ha}^{-1}
  • Residual ratoon effects of T9 yielded NMC = 92.4 imes 10^{3} ext{ ha}^{-1}, yield = 79.6 ext{ t ha}^{-1}, sugar yield = 9.36 ext{ t ha}^{-1}
  • T5 and T8 (bio-compost at 5 t ha^-1 and 7.5 t ha^-1 respectively) were close to T9 in terms of yield and were significantly higher than control
  • Sugar yield composition: sugar yield correlated with CCS% and cane yield
  • Nutrient uptake (Table 2, plant and ratoon):
  • T9 registered the highest total uptake of major nutrients in both plant and ratoon; plant N ≈ 196.9 ext{ kg ha}^{-1}, plant K ≈ 221.92 ext{ kg ha}^{-1}, ratoon N ≈ 195.40 ext{ kg ha}^{-1}, ratoon K ≈ 198.5 ext{ kg ha}^{-1}; micro-nutrient uptake (Zn, Fe, Mn) also elevated (Zn ≈ 56.13 mg kg^-1, Fe ≈ 679.61 mg kg^-1, Mn ≈ 239.96 mg kg^-1 in plant tissues for T9)
  • Soil properties after harvest (Table 3):
  • pH: T9 = 7.69; EC = 0.39 dS/m; Organic Carbon = 7.3 g/kg; Bulk density = 1.32 g cm^-3; Ca2+ Mg2+ = 12.85 (m/L)
  • Available N = 265.4 kg ha^-1; P2O5 = 37.9 kg ha^-1; K2O = 136.6 kg ha^-1 in T9
  • Compared with control (T1): pH 8.29; EC 0.28 dS/m; Organic Carbon 4.4 g/kg; Bulk density 1.38 g cm^-3; Available N 226.4 kg ha^-1; P2O5 23.4 kg ha^-1; K2O 114.8 kg ha^-1
  • Microbial populations post-harvest (Table 5):
  • T9: Bacteria 42.8×10^6 g^-1; Fungi 29.3×10^4 g^-1; Actinomycetes 28.7×10^2 g^-1; Acetobacter 34.8×10^6 ml^-1
  • Control had the lowest counts across groups
  • Soil enzyme activities post-harvest (Table 6):
  • β-glucosidase: T9 = 760 μg PNG g^-1 dwt h^-1; Urease = 44 NH3-N g^-1 h^-1; Acid phosphatase = 1100 μg p-NPP g^-1 h^-1; Dehydrogenase = 1.98 μg TTC g^-1 h^-1
  • Enzyme activities generally increased with organic inputs and biofertilizers; highest in T9

• Interpretation and implications

  • Integrated nutrient management, combining organic inputs (bio-compost), biofertilizers (Acetobacter, PSB, and Trichoderma), and reduced inorganic NPK, can sustain or improve sugarcane yield and quality in calcareous soils where phosphorus availability and nitrogen use efficiency are limiting
  • Bio-compost acts as a key driver for soil organic carbon, nutrient availability, microbial proliferation, and enzyme activities, thereby enhancing soil health and crop productivity
  • Biofertilizers enhance nitrogen fixation and phosphorus solubilization, enabling a reduction in chemical fertilizer inputs by ~25% without sacrificing yield; in fact, plant and ratoon performance improved with T9
  • Soil health improvements (lower pH in alkaline soils, higher CEC via organic matter buildup, increased micro-nutrients) contribute to sustained productivity and potential resilience against nutrient imbalances
  • The observed increase in enzyme activities (β-glucosidase, urease, acid phosphatase, dehydrogenase) and microbial populations under integrated management indicates a more active rhizosphere microbiome, which supports nutrient cycling and plant nutrition

• Conclusions drawn by authors

  • Integrated use of bio-compost with biofertilizers and inorganic fertilizer, including acetobacter and PSB, reduces the need for higher chemical NPK inputs by 25% while improving soil fertility, enzymatic activity, microbial populations, and overall sugarcane productivity and sugar recovery
  • The approach enhances soil health and sustainability of the sugarcane plant–ratoon system in calcareous soils within the Indo-Gangetic Plains

• Notes on data access and authorship

  • Data and materials available on reasonable request from corresponding author
  • Authors acknowledge collaboration; affiliations span several research institutes in Bihar and neighboring regions

• References and methods cited (selected topics)

  • Standard soil and plant nutrient analyses (Walkley–Black SOM, alkaline permanganate N, Olsen P, flame photometry K)
  • Microbiological and enzymatic assay methods (plate-count, PNG substrate for β-glucosidase, urease assay, p-NPP for acid phosphatase, TTC for dehydrogenase)
  • Prior work on biofertilizers, phosphate solubilizing bacteria, nitrogen fixation in sugarcane, and integrated nutrient management in sugarcane and related systems

• Key data snapshots (for quick review)

  • Highest plant NMC: 103.0 imes 10^{3} ext{ ha}^{-1}; highest plant cane yield: 85.8 ext{ t ha}^{-1}; highest plant sugar yield: 11.21 ext{ t ha}^{-1} (T9)
  • Residual ratoon: NMC 92.4 imes 10^{3} ext{ ha}^{-1}; yield 79.6 ext{ t ha}^{-1}; sugar yield 9.36 ext{ t ha}^{-1} (T9)
  • Post-harvest soil: pH 7.69; EC 0.39 dS/m; Organic Carbon 7.3 g/kg; Bulk density 1.32 g cm^-3
  • Available nutrients in T9: N 265.4 kg ha^-1; P2O5 37.9 kg ha^-1; K2O 136.6 kg ha^-1
  • Micro-nutrients in soil (T9): Fe 8.50 mg kg^-1; Zn 0.79; Cu 0.89; Mn 2.89 mg kg^-1
  • Post-harvest enzyme activities (T9): β-glucosidase 760 μg PNG g^-1 dwt h^-1; Urease 44 NH3-N g^-1 h^-1; Acid phosphatase 1100 μg p-NPP g^-1 h^-1; Dehydrogenase 1.98 μg TTC g^-1 h^-1

• Overall takeaway

  • For calcareous soils in sub-tropical India, a balanced, integrated nutrient strategy that combines 75% RDF with organic inputs and biofertilizers yields superior plant and ratoon performance, improves soil health indicators, and reduces the chemical fertilizer burden without compromising yield or quality.