Harnessing the power of integrated nutrient management for productive and resilient maize cultivation
For decades, the story of increasing crop yields has been heavily reliant on a single character: chemical fertilizer. While effective in the short term, this over-dependence has led to degraded soil, polluted waterways, and unsustainable farming costs. But what if there was a way to harness the natural power of the soil itself to produce bountiful harvests? Emerging research is turning the page to a new, more sustainable narrative—one where green manure and chemical fertilizers work in concert to meet the precise nutrient needs of maize.
This approach, known as the "targeted yield" strategy, moves away from one-size-fits-all fertilization. Instead, it uses soil testing and precise calculations to determine the exact amount of nutrients required to reach a desired yield goal. By integrating organic matter from green manure with judicious amounts of chemical fertilizer, farmers can build healthy soils, reduce environmental impact, and achieve impressive, sustainable maize production.
The targeted yield approach is a paradigm shift from "fertilizing the soil" in a general way to "fertilizing the crop" with precision. It is grounded in the understanding that a crop's nutrient uptake is directly and linearly related to the nutrients available from both the soil and any added fertilizers 9 .
This method is formalized through the Soil Test Crop Response (STCR) approach. It doesn't guess; it calculates. The STCR method uses a set of equations that consider three critical factors to generate a custom fertilizer prescription 9 :
When green manures are added to the equation, a fourth factor is considered: the Contribution from Organic Manure (%C-OM). This integrated system ensures that every nutrient source is accounted for, minimizing waste and maximizing efficiency.
N, P, K needed per 100kg of grain
Soil's inherent nutrient supply capacity
How well fertilizers deliver nutrients
Nutrient contribution from green manure
A landmark long-term field experiment conducted on a rainfed Inceptisol in northern India provides compelling evidence for the effectiveness of this integrated approach 1 2 . Over twelve years, researchers tested ten different fertilization strategies to see which would best sustain maize yield and soil health.
The experiment was designed to mimic real-world conditions on a nutrient-depleted, sandy loam soil. The researchers compared an unfertilized control plot against various combinations of chemical nitrogen (applied at 20, 30, and 40 kg per hectare) and different organic sources 1 2 :
Applied at 10 tons per hectare
Incorporated as in-situ biomass
Applied at 5 tons per hectare
No fertilizer application
The team then meticulously tracked key indicators over more than a decade: maize grain yield, soil organic carbon (SOC) levels, major nutrient levels (N, P, K), and rain water use efficiency (RWUE).
Baseline measurements of soil health
10 different fertilization strategies
12 years of data collection
Comparing yield and soil health indicators
The long-term data painted a clear picture: the combination of organic and inorganic fertilizers consistently outperformed either one alone.
| Treatment | Average Maize Yield (kg/ha) | Soil Organic Carbon (g/kg) |
|---|---|---|
| Control (No Fertilizer) | Low (Baseline) | Decreased from initial |
| 40 kg N ha⁻¹ (Chemical Only) | Moderate | Moderate |
| 10 t/ha FYM (Organic Only) | Good | Improved |
| 40 kg N ha⁻¹ + 10 t/ha FYM | Highest | Highest (1.44x control) |
Source: 1
| Treatment | Sustainability Yield Index (SYI) | Rain Water Use Efficiency (kg/ha/mm) |
|---|---|---|
| Control (No Fertilizer) | Lowest | Lowest |
| 40 kg N ha⁻¹ (Chemical Only) | Moderate | Moderate |
| 40 kg N ha⁻¹ + 10 t/ha FYM | 49.3% | 2.74 |
Source: 1
Research from a 40-year soybean-maize rotation trial found that manure application increased crop yields by significantly promoting nitrogen use efficiency. The organic matter helps retain nitrogen in the root zone, making it available to plants over a longer period and reducing losses to the environment 6 .
A study in the yellow soils of China's Yunnan-Guizhou Plateau found that leguminous green manures like alfalfa and common vetch drastically improved phosphorus fertilizer use efficiency. The green manures help solubilize fixed soil phosphorus, making it available for the maize crop 4 .
Implementing a targeted yield approach with green manure requires a specific set of tools and inputs. The table below details the essential "research reagents" and their functions based on the experiments cited.
| Item | Function & Application |
|---|---|
| Soil Testing Kit | The foundational tool for measuring initial soil pH, organic carbon, and available N, P, and K to inform the fertilizer prescription. |
| Leguminous Green Manures (e.g., Sunhemp, Alfalfa, Common Vetch) | Grown and incorporated into the soil to fix atmospheric nitrogen, add organic matter, and improve soil structure. |
| Farmyard Manure (FYM) | An organic amendment used to build soil organic carbon, slowly release a spectrum of nutrients, and enhance soil biological activity. |
| Chemical Fertilizers (Urea, DAP, SSP, MOP) | Provide readily available forms of N, P, and K in precise amounts to meet the crop's immediate nutrient demands and fill the gap left by soil and organic sources. |
| Fertilizer Prescription Equations | The mathematical formulas that integrate soil test values, target yield, and nutrient contribution factors to calculate the exact fertilizer requirement. |
The evidence is clear: the future of productive and sustainable maize cultivation lies in moving beyond conventional practices. The conjoint use of green manure and chemical fertilizers, guided by the precision of the targeted yield approach, offers a scientifically-backed path forward.
This strategy does not simply extract from the land; it invests in it. By building soil organic carbon, enhancing nutrient use efficiency, and creating a resilient soil ecosystem, farmers can achieve high yields today without compromising the ability of future generations to do the same. It's a win-win solution where agricultural productivity and environmental health grow together.
This integrated system represents a sophisticated and sustainable path for maize production, turning the challenge of feeding a growing population into an opportunity to restore our agricultural soils.