Introduction
Corn, sometimes referred to as maize, is one of the most extensively cultivated crops in the world. It is used as a staple food and is an essential part of industrial and animal feed. The management of nutrients, especially nitrogen, must be carefully considered in order to achieve the best yields. One of the most important nutrients for maize’s growth, development, and productivity is nitrogen. A nitrogen deficiency in maize results in stunted growth, lower yields, and lower-quality crops.
Nitrogen plays a vital role in promoting vigorous, green growth in maize plants, directly contributing to higher yields and improved grain quality. For optimal development, maize requires both nitrogen and phosphorus shortly after germination to support the growth of stems, leaves, and ear formation. However, the highest demand for nitrogen occurs during the peak growth phase, typically in the month leading up to tasseling and silking, when the plant’s nutrient needs are greatest.
Moreover, nitrogen also plays a central role in photosynthesis, protein synthesis, and chlorophyll production. When maize plants don’t receive enough nitrogen, their growth is impaired, and they exhibit specific visual symptoms. Nitrogen deficiency in maize is common, especially in soils with low organic matter or improper fertilization practices.
This article will discuss the signs of maize nitrogen deficit, its underlying causes, and workable ways to avoid and deal with the problem. This book will help you make sure your maize crop grows, regardless of how big or small your agribusiness is.
Symptoms of Nitrogen Deficiency in Maize
Plants experiencing nitrogen deficiency often display stunted or uneven growth. Their leaves may turn a light green color, with the oldest leaves showing yellowing and necrosis (tissue death) that begins at the leaf tips and progresses inward.
Sulfur and nitrogen deficiencies can have similar symptoms, but they can be differentiated by the leaves they first impact. Younger leaves are usually affected by sulfur deficiency, but older leaves are initially affected by nitrogen shortages that cause yellowing or paling.
Identifying nitrogen deficiency early is crucial for timely intervention. Here are the most common symptoms to watch for:
a). Yellowing of Leaves (Chlorosis)
Beginning at the tips and moving inward, the lower, older leaves close to the plant’s base start to turn yellow. This occurs as a result of nitrogen’s mobility, which allows the plant to move it from older leaves to support the growth of fresh ones.
b). Stunted Growth
Nitrogen-deficient maize plants often appear smaller and grow more slowly than healthy plants. The stems may become thin and weak, making the plants prone to lodging.
c). Poor Ear Development
Insufficient nitrogen can lead to smaller or poorly formed ears, directly impacting yield and grain quality.
d). Reduced Tillering
In severe cases, the plant may produce fewer tillers (side shoots), further reducing the potential yield.
Causes of Nitrogen Deficiency in Maize
Understanding the root causes of nitrogen deficiency can help you take preventive measures. Here are the most common reasons:
a). Low Soil Nitrogen Levels
Insufficient nitrogen in the soil is a common issue, particularly in soils with low organic matter content or those that have been intensively cultivated over time. Organic matter is a key source of nitrogen, and when it is depleted, the soil’s ability to provide this essential nutrient diminishes. Over-farming exacerbates the problem, as continuous cropping without adequate nutrient replenishment depletes nitrogen reserves.
This deficiency can hinder plant growth and productivity, making it crucial to monitor soil health and implement practices like crop rotation, organic amendments, or targeted fertilization to restore nitrogen levels and maintain soil fertility.
b). Improper Fertilization Practices
Incorrect fertilization practices, such as applying insufficient amounts of nitrogen or timing applications poorly, are significant contributors to nitrogen deficiency in crops. For instance, studies show that maize requires approximately 250–300 kg of nitrogen per hectare to achieve optimal yields, but inadequate application can reduce yields by up to 30–50%.
Additionally, applying nitrogen too early or too late in the growing season can limit its availability during critical growth stages, such as the period leading up to tasseling and silking, when the plant’s nitrogen demand peaks. Research indicates that improper timing can result in nitrogen losses of 20–50% due to leaching, volatilization, or runoff, further exacerbating deficiencies.
To maximize efficiency, farmers are encouraged to adopt precision agriculture techniques, such as split applications or soil testing, to ensure nitrogen is applied in the right amounts and at the right time, tailored to the crop’s growth cycle and soil conditions.
c). Leaching and Runoff
Excessive irrigation or heavy rainfall can cause substantial nitrogen loss through runoff and leaching, making it unavailable to plants. Since nitrogen is very soluble in water, especially when it comes to nitrates (NO₃⁻), it is likely to be washed out of the root zone. According to studies, in regions with high rainfall or inadequate drainage, leaching may cause up to 30–50% of applied nitrogen to be lost.
For instance, nitrogen losses can amount to 40–60 kg per hectare per year in areas where annual rainfall exceeds 1,000 mm. In a similar vein, runoff from crops that receive excessive irrigation can introduce nitrogen into adjacent water bodies, causing eutrophication and other environmental problems.
To mitigate these losses, farmers can adopt practices such as controlled irrigation, using slow-release fertilizers, or planting cover crops to absorb excess nitrogen. Additionally, implementing conservation tillage and creating buffer zones can help reduce runoff, ensuring that more nitrogen remains available for crop uptake and improving overall nutrient use efficiency.
d). Soil pH Imbalance
Soil pH plays a critical role in nitrogen availability and uptake by maize plants. When soils are too alkaline (high pH) or too acidic (low pH), the plant’s ability to absorb nitrogen is significantly hindered. Ideally, maize thrives in soil with a pH range of 5.8 to 7.0.
In acidic soils (pH below 5.5), nitrogen conversion processes, such as nitrification, are slowed down, reducing the availability of nitrate (NO₃⁻), the primary form of nitrogen absorbed by plants. Studies show that in highly acidic soils (pH < 5.0), nitrogen uptake efficiency can drop by 20–40%, leading to stunted growth and reduced yields.
On the other hand, in alkaline soils (pH above 7.5), ammonia volatilization increases, causing nitrogen losses of up to 30–50% when urea-based fertilizers are applied. Additionally, high pH levels can limit the solubility of certain nitrogen compounds, further restricting availability. For example, research indicates that maize yields can decrease by 15–25% in soils with a pH above 8.0 due to poor nitrogen uptake.
To address pH imbalances, farmers can apply lime to acidic soils to raise pH or use sulfur-based amendments to lower pH in alkaline soils. Regular soil testing and pH monitoring are essential to maintain optimal conditions for nitrogen absorption and ensure healthy maize growth.
e). Poor Crop Rotation Practices
Continuous maize cultivation without rotating with nitrogen-fixing crops, such as legumes, depletes soil nitrogen over time. Maize requires 250–300 kg of nitrogen per hectare, and without rotation, soil nitrogen reserves diminish, reducing productivity by 20–40% over 5–10 years. Integrating legumes like soybeans or beans, which fix 50–200 kg of nitrogen per hectare, can replenish soil nitrogen and boost maize yields by 10–30%.
Sustainable crop rotation with legumes not only maintains soil nitrogen but also improves soil health, reduces pests, and enhances farm productivity. Diversifying cropping systems with nitrogen-fixing crops ensures long-term fertility and agricultural sustainability, reducing reliance on synthetic fertilizers by 25–50%.
How to Fix Nitrogen Deficiency in Maize
If you’ve identified nitrogen deficiency in your maize crop, don’t worry—here is the way to address the issue:
a). Use Foliar Sprays
Foliar sprays offer a rapid and efficient means of supplying nutrients straight to the plant, making them a useful remedy for severe nitrogen deficit in maize. Foliar sprays, when used properly, enable maize plants to receive nitrogen through their leaves, avoiding problems with the soil such limited root uptake or insufficient fertilizer availability.
For maize, a common foliar spray involves dissolving urea at a rate of 5 grams per liter of water. Urea is a highly soluble nitrogen source, making it ideal for foliar application. Studies have shown that foliar spraying can improve nitrogen uptake efficiency by up to 90%, compared to soil application, especially in cases where soil conditions hinder nutrient absorption.
Research indicates that foliar sprays can increase maize yields by 10–20% when applied during critical growth stages, such as the V6 stage (when the plant has six visible leaves) or during tasseling and silking. Additionally, foliar application can reduce nitrogen losses caused by leaching or volatilization, which can account for up to 30–50% of applied nitrogen in traditional soil fertilization methods.
However, it is important to apply foliar sprays during cooler parts of the day, such as early morning or late afternoon, to avoid leaf burn and maximize absorption. While foliar sprays provide a quick fix, they should be used in conjunction with soil-based fertilization for long-term nutrient management. This combined approach ensures sustained nitrogen availability and optimal maize growth throughout the growing season.
Preventing Nitrogen Deficiency in Maize
a). Conduct Regular Soil Tests
One essential procedure for efficient nutrient management in maize farming is routine soil testing. Farmers may precisely measure nitrogen levels, pH, and other important soil characteristics by conducting soil testing once a year and one to two months prior to planting. Making educated fertilization decisions and guaranteeing the crop has the best possible nutrient availability require this knowledge.
b). Adjust Soil pH
Adjusting soil pH is critical for optimizing nitrogen availability in maize cultivation, as the crop thrives in a pH range of 6–7. When soil pH falls below 6, nitrogen uptake is hindered due to reduced nitrification and nutrient solubility. Applying lime at a rate of 0.2–0.5 tons per hectare can effectively raise pH levels, improving nitrogen availability and enhancing maize growth. Studies show that correcting acidic soils can increase nitrogen use efficiency by 20–40% and boost yields by 10–25%.
c). Apply Organic Manure
Applying organic manure at a rate of 400 kg per acre is a highly effective strategy to improve soil health and nitrogen management in maize cultivation. Organic manure enhances soil water retention, reducing the risk of nitrogen leaching, which can account for up to 30–50% of nitrogen losses in heavily irrigated or high-rainfall areas. Studies indicate that incorporating organic manure can increase soil organic matter by 10–20%, improving nutrient availability and boosting maize yields by 15–25%.
d). Avoid Waterlogging
Avoiding waterlogging is essential for maintaining optimal nitrogen levels in maize fields, as excess water can lead to nitrogen loss through leaching and denitrification. Proper drainage can be achieved by maintaining high ridges and keeping troughs free of weeds, which ensures efficient water movement and prevents stagnation.
e). Control Weeds
In order to reduce competition for vital resources like sunlight, water, and nutrients, it is imperative to keep the field clear of weeds. One important component needed for the proper growth and development of maize plants is nitrogen, which can drastically lower in the soil. Effective weed control guarantees that maize plants have unhindered access to the nitrogen they require, which raises crop output. To maximize nutrient uptake and promote strong plant growth, regular weeding—either by hand or with the use of suitable herbicides—is advised during the crucial growth stages of the maize crop.
f). Choose Efficient Varieties
In order to maximize crop performance, it is crucial to use maize types that have been specially bred for effective nitrogen utilization. Under circumstances where nitrogen availability is restricted, these types may efficiently absorb and utilize nitrogen from the soil. Such effective maize cultivars allow farmers to reduce their reliance on synthetic nitrogen fertilizers while increasing yields. By doing this, input prices are reduced and environmental effects like nitrate leaching and greenhouse gas emissions from overuse of fertilizer are reduced. Make sure the variety you choose is compatible with the growth conditions and the overall sustainability of the farming system by taking into account aspects like the local climate, soil type, and pest and disease resistance.
g). Preventing Soil Erosion
Use drip irrigation, less tillage, better drainage, and the planting of cover crops (such as wheat, rye, and oats) as erosion control techniques. To reduce nutrient loss, plant perpendicular to slopes and avoid compacting the soil.
h). Rotate with Legumes
Soil nitrogen can be sustainably restored through crop rotation or intercropping with nitrogen-fixing legumes like soybeans, cowpeas, and beans, or trees such as Sesbania and Leucaena. These plants work with rhizobia bacteria to convert atmospheric nitrogen into plant-usable forms, reducing reliance on synthetic fertilizers. Research shows that legume-maize rotations can add 30–60 kg of nitrogen per hectare each year, while intercropping with cowpeas can increase maize yields by up to 25%. Nitrogen-fixing trees like Leucaena can supply up to 200 kg of nitrogen per hectare annually, making this approach crucial for maintaining soil fertility and promoting sustainable agriculture.
i). Retain Crop Residues
An efficient method of improving soil fertility and addressing nitrogen deficits in maize agriculture is to leave crop remains on the field after harvest instead of burning them. Remainders release important nutrients as they break down, such as 30 to 60 kg of nitrogen per acre, depending on the kind and quantity of material. Higher yields and healthier crops are supported by this natural nutrient recycling, which also enhances soil structure, moisture retention, and organic matter.
In addition to wasting nutrients, burning residues damage the long-term health of soil by releasing greenhouse gases and destroying beneficial bacteria. Using residues in techniques like mulching and low tillage improves water retention, inhibits weed growth, and lessens soil erosion. In addition to reducing dependency on artificial fertilizers and guaranteeing nutrient availability for subsequent crops, retaining crop residue supports sustainable agriculture.
Also Read About: Potassium Deficiency in Maize
Conclusion
In maize, nitrogen shortage is a prevalent but controllable problem that can have a big influence on crop quality and output. By identifying the signs early, comprehending the reasons, and putting good solutions in place, you can make sure your maize plants get the nutrients they require to flourish. Recall that the basis of a successful crop is healthy soil. Preventing nitrogen deficiency and attaining the best possible maize yields need consistent soil testing, appropriate fertilizer, and sustainable agricultural methods.
