Improving nutrient use efficiency is not only essential for crop health and productivity: it can also help growers reduce input costs and minimize environmental impacts that come with the overapplication of fertilizer.
Integrated Plant Nutrient Management, or IPNM, is a framework through which this can be achieved. Like Integrated Pest Management, IPNM draws on both organic and chemical solutions to create fertilizer programs that optimize nutrient use efficiency by considering long-term soil health, crop productivity, nutrient balancing, and the efficient and sustainable use of fertilizer inputs.
When used in an IPNM approach, beneficial microbes possess remarkable abilities to enhance nutrient use efficiency. By solubilizing otherwise inaccessible nutrients and stimulating plant functions involved in nutrient uptake, assimilation, and utilization, these microscopic allies play a pivotal role in optimizing nutrient availability. Integrating beneficial microbes into your nutrient management practices can lead to significant improvements in crop performance while reducing fertilizer requirements.
This article explores the relationship between nutrient use efficiency and beneficial microbes and delves into actionable steps one can take to leverage their potential as part of any nutrient management strategy.
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Nutrient Use Efficiency
Given rising fertilizer costs and the substantial environmental consequences of synthetic fertilizer pollution, nutrient use efficiency (NUE) is something every grower should be paying close attention to. Suboptimal NUE increases fertilizer demands, and the overapplication of nitrogen fertilizers is one of agriculture’s most damaging sources of greenhouse gas emissions and soil degradation. NUE measures the ability of plants to absorb and use nutrients effectively. Put simply,
higher NUE levels mean fewer inputs will be needed to achieve optimal yields. But nutrient availability through fertilization is only one aspect of plant nutrition: nutrient uptake, assimilation, and utilization matter just as much, and it is these factors that determine NUE.
The use efficiency of individual nutrients is often dependent on the levels of other nutrients in the soil. For example, nitrogen use efficiency significantly improves when potassium and sulfur are at appropriate levels, as they mediate plant uptake and ensure the conversion of nitrogen to amino acids and proteins. The result is less nitrogen leaching and a reduction in both N2O emissions and total fertilizer demands.
Nitrogen is an easy example, but the principles apply to every plant nutrient: fertilizers cannot be considered in isolation. Rather, a balanced fertilization approach is key to improving nutrient use efficiency.
Why Balanced Fertilization Matters
Nutrients constantly cycle in and out of soil over time. The process, known as the nutrient cycle, means that the levels of absolute and available nutrients are constantly in a state of flux. Manipulating this cycle through crop input selection and farming practices to encourage an optimal supply and distribution of nutrients through time and changing environmental conditions is achieved through balanced fertilization strategies.
The nutrient cycle is far more complex than a simple “nutrients in, nutrients out” formula. Therefore, it is difficult, if not impossible, to achieve balanced fertilization with simplistic fertilization programs. Balanced fertilization—and subsequent improvements in nutrient use efficiency—requires integrating a diverse set of nutrient management strategies.
Integrated Plant Nutrient Management Strategies
Integrated Plant Nutrient Management (IPNM) is a framework in which growers apply a mix of conventional and organic inputs and farming practices. IPNM is context-dependent, and the right mix of tactics will vary depending on cropping systems, soil type, existing deficiencies, local climatic conditions, and more.
However, all IPNM approaches will include some fundamental principles. They adhere to the 4R approach to fertilization: applying the right fertilizer at the right rate, matching with the right crop growing period, and applying it in the right place. The 4R approach leverages an understanding of nutrient cycles to time fertilizer applications when plant uptake, assimilation, and utilization are highest to maximize use efficiency and minimize pollution.
IPNM also prioritizes soil health. The addition of biofertilizers and organic matter improves the fertility, water-retaining, and nutrient-holding capacities of soil. Perhaps most importantly, by complementing fertilizers with soil-building practices and organic inputs, integrated nutrient management strategies recognize the unique role of beneficial microbes in improving nutrient use efficiency.
How Beneficial Microbes Improve Nutrient Use Efficiency
Beneficial microbes include any soil bacteria or fungi that stimulate or enhance biological processes in soil, plant, and the rhizosphere. Beneficial microbes can improve nutrient use efficiency by solubilizing otherwise unavailable nutrients and by stimulating biological plant functions involved in the uptake, assimilation, and utilization of essential nutrients.
Beneficial microbes have been proven to improve the use efficiency of both organic and chemical sources of nitrogen, potassium, and phosphorus (NPK), along with scores of other micronutrients.
Many beneficial microbes exist naturally in agricultural soils. But the overapplication of chemical NPK fertilizers degrades beneficial microbial populations and often leads to nutrient imbalances. The resulting decline in nutrient use efficiency is addressed by applying more salt-based fertilizer, which degrades soil health even further—a tragic vicious cycle.
Introducing beneficial microbes—and encouraging soil conditions in which they can thrive—as part of an IPNM strategy can improve nutrient use efficiency and long-term soil health, helping growers break free of this vicious cycle.
Integrating Beneficial Microbes to Enhance Nutrient Use Efficiency
You can harness the benefits of beneficial microbes by incorporating soil-building practices and high-quality microbial products into your integrated nutrient management program. These are a few strategies to prioritize:
Practice crop rotation and diversity: Rotating through diverse crops promotes microbial biodiversity in the soil, which contributes to improved nutrient cycling and availability.
Increase soil organic matter: Incorporate organic matter from compost and cover crops. Increasing organic matter content improves soil structure, water retention, and nutrient-holding capacity, creating a favorable environment for beneficial microbes to thrive.
Introduce beneficial microbial inoculants: Add high-quality microbial inoculants that promote nutrient solubilization, enhance nutrient uptake, and improve plant growth. Impello’s Continuμm™ is a blend of different plant growth-promoting rhizobacteria (PGPR), chosen for their ability to solubilize essential nutrients and stimulate plant processes involved in nutrient uptake and utilization.
Inoculate during key growth stages: Time applications of Continuμm™ to coincide with critical plant growth stages, including seed germination, transplanting, or early vegetative growth. This ensures optimal colonization of microbial populations in the rhizosphere.
Incorporate other biostimulants: In addition to inoculants, other biostimulant products, like—amino acids and biofertilizers—can be used to encourage microbial activity and nutrient use efficiency even further.
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