Nitrogen Management - Keep It Simple & Look Outside the Square

Nitrogen has been an important component of food product in agriculture for decades. Since the late 1990's there has been increased concerns about its use and the subsequent effects on the environment, especially around sensitive waterway systems. It is now that time again that the nitrogen football is being passed around politics and the media. As usual, emotions are taking the lead between politicians, growers, and government departments. So, for a moment let’s take emotion out of the equation.

Nitrogen is one of the most mobile elements in our soil and as such there are several pathways for its loss. The most common nitrogen product utilised in agriculture now is urea, a product that has been available for decades. Now it is also at historical highs, meaning that grower's costs are being increased with little or no increase for the food and fibre that they produce. The answer to date has been to investigate a nitrogen ceiling for growers to abide to in order to reduce the impact on the environment. So, in areas such as North Queensland we are trying to legislate a highly mobile nutrient, in an area with some of the highest and most unpredictable rainfall in the country, with some of the higher nitrogen use crops in horticulture. Sound a little crazy? The answer from successive governments, on both sides, has been to question the science, repeat the same research under a different regime, and try to set new levels. There is a popular saying "the definition of insanity is repeating a process and expecting a different outcome". Subsequently, the uptake by industry and growers has been less than enthusiastic.

So why haven't we taken the plunge? The answer is simple. Because there are key drivers that are not currently being addressed for many of the stakeholders in the industry. Growers need to be made aware of solutions available in the marketplace and that they have advantages. Agronomists and industry need the independent data on product performance and they work in the manner prescribed. Rural merchandise stores need to know that they have a commercial alternative to urea that growers and agronomists will embrace. The purpose of this article is not to suggest that the science is wrong, nor that we should not be setting a nitrogen use level. I do agree with much of the science and that a suitable BMP level needs to be determined. There is no silver bullet, yet we are looking for one. But this topic is for another day and potentially another article. This article will cover three simple factors with nitrogen that you should be considering this season and every season.

Listen to the Plant

Because nitrogen is mobile you need to understand the plant's ability to uptake the product. This is generally done through the root system (except for foliar application). Yet how many of you have looked at the root system after harvest? A healthy root system can uptake nutrients more efficiently, access water, survive excessive rainfall events and thus regulate plant health. If you have a poor root system, applying high rates of nitrogen less often will only leads to leaching past the effective root zone. In this case you will need to devise a plan for smaller amounts more often, which has its efficiency benefits as well. The depth of the root system will also be able to give you a strategy for nitrogen use during excessive rainfall events. A deeper root system, the more nitrogen is retained by the plant after irrigation or rainfall. Match application rates to what the plant can uptake efficiently.

Measure, Measure, Measure

This is a common theme of my articles. Utilise as many easy measurement systems as possible at your disposal. With regards to soil tests, I still see so many tests being focused on the surface. If you know how deep your roots are going, then invest in a deep soil test as well. It takes the guesswork out of what your plant can access later in the season and once again, potentially saving you hundreds on your nutrition expenditure. Leaf tests are being utilised by many farms. This is a great way to see what you plant is doing now. When used in conjunction with soil tests they can be a very effective proactive tool for the season, rather than waiting for deficiencies to appear in the crop. Moisture meters can also be a very good tool for nitrogen management. If you understand how nitrogen moves through your profile, moisture meters can aid in understanding where your applications are with regards to your root structure.

Nitrogen Efficiency Products

Urea is currently the dominant nitrogen product supplied in the marketplace. It is simple to obtain and yet it is also an old technology with inherent limitations. In the marketplace there are several technologies available that can improve the uptake of nitrogen or reduce the losses. Some can be directly applied to established products, whist other are standalone products.

Urea efficiency products have been available for several years now. Most are coated products that are applied directly to the granule, either coating the outside or embedding into the granule. Some products reduce volatilisation, slow breakdown of the granule, reduce/increase the activity of microbes involved in breakdown the granule, or provide a carbon source to reduce leaching.

Urea Ammonium Nitrate (UAN) is an increasingly popular form of nitrogen. It is a high analysis liquid containing all three forms of nitrogen. It does however suffer some of the inefficiencies of urea. Like urea there are currently several options in the marketplace focusing on reducing the loss pathways of this product.

As well as additives there have been an increase in other products designed to improve the efficiencies within the nitrogen processes. Most of these to date have been centred around biology and other related technologies.

So why look at these products? The two main reasons are cost and flexibility. Enhanced efficiency products mean that you can utilise less product to maintain your current yield levels. This is because less of the nitrogen is lost through the various avenues. The amount of this reduction will be dependent upon the manufacturer's literature. Be sure to check the data. In addition, check how the product works, as this will have a direct effect on your operations and how it can be utilised. Flexibility is also an understated by-product of this solution. If you could grow your current crop with less nitrogen and are meeting the current legislative requirements, it means that your potential to grow higher yield crops when more favourable conditions presents itself. This provides a nitrogen flexibility that has never been explored in our industry to date.

By investigating the three simple steps and you will be well on your way to potentially improving your nutritional use efficiency this season. Worst case you will begin to understand further what is going on in your soil and your crops, which isn't such a bad thing?