4-R Nutrient Management
By. D. Stephen Ellery, P.Ag, CCA
The 4-R Nutrient Management principles are formally recognized guidelines for nutrient management in crops. The principles are based on applying the Right fertilizer source, at the Right rate, at the right time and in the Right place. Producers are becoming aware there are multiple economic, environmental, and social benefits to implementing a 4-R Nutrient Management strategy on their farm. This article is aimed to outline some of the basic and advanced principles and benefits of 4-R Nutrient Stewardship and give you some ideas or strategies that you can implement on your operation. It should be noted that the backbone of any fertility program is an understanding of your soils background fertility levels and production capabilities. Implementing a proper nutrient management plan requires soil testing coupled with yield-based production goals as a minimum baseline to get started, beyond that there are more advanced things to improve your nutrient use efficiency.
The first R of 4-R Nutrient Stewardship is Right Source, and this principle pertains to matching the appropriate fertilizer type to the crop needs and environmental conditions. The idea behind this is to minimize the application of unneeded fertilizers and supply what the crop needs in a plant available form to achieve target yields. It is important to understand that of the 4-R’s, Source is one of the most confusing and can result in major economic impacts on your operation. Economic benefits from using the right source of fertilizer include reduction in total fertilizer use for a producer and increased nutrient use efficiency. Social and environmental benefits include a reduced potential fertilizer leeching and run-off and reduce mining and manufacturing of mineral fertilizers.
The second R I am going to talk about is the Right Rate. The principles pertaining to this element of a nutrient management plan are focused on supplying the appropriate rate of fertilizer to fulfill crop demands. This is done by using yield-based targets (or goals) and background soil fertility levels to set appropriate fertilizer rates. These should also be adjusted based on soil type and climate conditions to minimize nutrient losses and maximize uptake as some soils are prone to leaching certain types of fertilizer. Instances where probability for fertilizer losses are high may warrant the use of slow-release fertilizers or split applications to increase nutrient use efficiency. A more advanced techniques to match fertilizer requirements is to implement a variable rate fertility program. This involves programming the seeding implement to apply varying rates of fertilizer across different productivity (or management) zones identified in a producer’s fields.
Applying your fertilizer at the Right Time is also an important factor in an effective nutrient management plan. Ensuring the crop has adequate nutrition when it needs it is vital to protecting yield potential of your crop. Some strategies for applying fertilizers at the right time include the use of slow-release fertilizers (ESN, Agrotain, Urease Inhibitors) and split applications of nutrients (top dressing, dribble). Depending on your soil and climate conditions implementing these practices can be beneficial economically, socially, and environmentally. One example would be a producer in an area with sandy soils and high precipitation, a split application of nitrogen fertilizer can prevent losses through leaching in the event of a large rain event and overapplying in the event of a drought. This saves the producer money as less fertilizer is lost through leaching and will subsequently need to be reapplied to maintain yields. In the event of a drought, the producer can skip the in-crop application and prevent over application of nitrogen. Applying fertilizer at the right time is also socially and environmentally conscious as it reduces total volumes of fertilizer being applied and leaching of fertilizer into waterways.
The final objective of the 4-R Nutrient principles is applying fertilizer in the right place. This is done to ensure nutrient availability is maximized for plant uptake when needed. Different fertilizer sources are susceptible to different loss pathways and manipulating placement can help reduce losses and increase availability. Nitrogen for example can be lost to different pathways including leaching, volatilization and denitrification all depending on both fertilizer source and placement. In its nitrate form, nitrogen is susceptible to loss through leaching or denitrification depending on soil type. Under heavy precipitation events, nitrate will tend to be lost through leaching whereas heavy soils with low infiltration rates will promote denitrification.
At Agrological Solutions we understand that fertility management is not a one size fits all recipe. Working with an agronomist who knows the local crops, climate and soil capabilities will help you maximize the efficiencies of any nutrient management plan. We are a local company based out of Havre, MT and have a proven track record for providing nutrient management plans on over 60,000 acres of cropland annually. We have been at the forefront in diversifying Chemfallow-Wheat rotations with pulse and oilseed crops on the Hi-Line since 2017. We have experience working with both synthetic (dry and liquid) and organic (manure) fertility programs on the Hi-Line in Montana. We strive to implement as many of the 4-R Nutrient Stewardship principles as possible to ensure minimal environmental impact and maximized returns for the producer.