![]() ![]() ![]() These types of losses are far greater with urea (46-0-0) than with ammonium nitrate fertilizers (34-0-0) and ammonium sulphate (21-0-0-24). Ammonia volatilization increases with increasing soil pH (alkaline soils), soil carbonate content and pH of the added fertilizer. Nitrogen from fertilizers containing ammonia or urea can be lost through volatilization as ammonia gas to the atmosphere in dry conditions. Under minimum till management, higher N immobilization in surface soil may reduce available N to crops.īanding N fertilizer in the soil can reduce immobilization losses. Immobilization can remove between 20 to 40% of inorganic N from the soil. Immobilization of ammonium nitrogen is slightly greater than immobilization of nitrate-nitrogen. Soil microbes compete with growing crops for N fertilizer, which may result in reduced crop growth. Organic N nust be mineralized by soil micro-organisms back into inorganic N forms for plants to utilize the N. Soil micro-organisms can convert nitrate and ammonium-N (inorganic N or plant available N) to organic N, which is not plant available. Nitrogen immobilization and losses Immobilization See wheat nutrition and fertilizer requirements – nitrogen for more information. II Nitrogen and phosphorus and content by plant development stage by Armand Brauer, A.B. Dry matter distribution by plan development stage, and Aerial parts of hard red spring wheat. Wheat dry matter accumulation and nitrogen uptake according to growth stage 1ġAdapted from Aerial parts of hard red spring wheat. shows growth stage where the flag leaf is fully expanded at Stage 8, the spike has cleared the collar at Stage 11, and kernel hard is Stage 15.įigure 1. N fertilizer must be in the root zone and available for uptake as crops enter their rapid growth period in the first month.įigure 1. Canola’s N uptake pattern is similar to that of wheat.Ĭanola N requirements are highest prior to bolting. The N uptake pattern and dry matter accumulation of spring wheat by growth stage is depicted in Figure 1 below. Wheat starts to require N at the 5-leaf stage, while the overall plant growth lags behind. Fall-applied Nitrogen: Risks and Benefits. ![]() See the following fact sheet for fall fertilizer information: Broadcast fertilization in the spring yielded the best results.Ī number of factors can cause N immobilization and losses, see ‘Nitrogen immobilization and losses’ below. Early winter applications of fertilizer appeared to be the worst, productivity dropped by as much as 15% over the same application in early spring. Compare costs, fertilizer can be more expensive in the spring making winter applications of urea viable, if there is limited loss from run-off, leaching and volatilization.Ī 2005 study in Lacombe by Agriculture and Agri-food Canada found ammonium nitrate applied at 100 kg N/hectare doubled productivity over unfertilized forage fields. Winter fertilization should only take place if snow is less than 4 inches deep and there is no ice layer, to allow granules to be ‘driven’ into the soil. N fertilizer requires moisture with canola and cereal crops, so N will be more effective after spring rains. There are advantages to both spring and fall fertilizing, but N supply is critical for early plant growth.Īdding additional N should be done within 4 to 5 weeks of seeding, but it can be more cost effective to apply it at seeding. Timingįertilizer timing depends on environmental conditions and the seasonal growth patterns of the plant. It is crucial to determine the best timing, placement, and rates of N fertilizer to apply. Nitrogen (N) is a significant component of proteins, which are essential for crop growth. ![]()
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