Nitrogen Expenditure (2014)

Currently most areas are experiencing a near perfect start to the season. Good early rainfall and mild conditions have provided the opportunity to reduce the weed seed bank and led to rapid early growth of crops. These favourable weather conditions in conjunction with low Urea prices have prompted discussion about the best bet Nitrogen strategy for 2014.

On face value, with good moisture, actively growing crops and low Urea prices, the easy decision would be to apply lavish amounts of Urea, targeting robust crop yields. However, careful consideration of the conditions at hand would suggest that 2014 may be a year to reduce expenditure on Nitrogen fertiliser. Should conditions remain favourable, 2014 is likely to provide astute managers with the opportunity to produce average (or better) yields with below average expenditure.

Factors which need to be considered when discussing expenditure on Nitrogen include:

Mineralisation – As discussed in the last News Bulletin, moist warm soils are likely to have led to significant mineralisation of Nitrogen. It is possible that in some areas soil mineralisation may have provided 50-60 kg N/ha, the equivalent of 110 to 130 kg/ha Urea.

Realistic Yield Targets – Astute managers will target realistic yields based on long term average yield data. History would suggest that in years where above average yields are achievable due to soil moisture being non-limiting, application of above average levels of Nitrogen are not necessarily required. The primary reason for this, is that if soils are moist late in the growing season, soil mineralisation is increased which provides much of the extra Nitrogen required to meet the demands of a higher yielding crop.

Many growers consistently target yields which are well above their long term average, which leads to higher expenditure on Nitrogen and associated increased business risk.

Following are some actual mean and median yields for a sample of client farms. The data represents a geographical spread across the RMS client base. Five of these seven data sets contain more than twenty consecutive years of data.

Historical N Usage – Nitrogen application rates have been high in recent years. This is particularly the case in the Temora region, where it seems choice of rate is based more on what the neighbours are doing than it is a calculation of estimated soil Nitrogen supply and demand.

Where previous years’ rates have been in excess of crop removal, it is likely that soil Nitrogen levels will be increasing.

Paddock History – Paddocks with a recent history of legume based pasture, will have a significant ability to respond to an above average season through increased mineralisation.

Crop Removal – 2013 crop yields in many areas were depressed due to dry conditions or frost. In this case, Nitrogen removal will have been reduced and hence carry over Nitrogen will be present.

Deep Soil Nitrogen Tests – In many areas DSN samples have only recently been taken. The limited number of tests that have been processed to date, have generally indicated higher levels of soil Nitrogen. In some cases, paddocks with a very long cropping history have adequate Nitrogen to produce grain yields above the long term average (assuming a conservative estimate of in-crop mineralisation)

As mentioned in the last News Bulletin, Deep Soil N Testing will provide valuable information for making topdressing decisions this year. In summary, a general analysis of the current situation would suggest that Nitrogen requirements for 2014 may be below average. This coupled with below average Urea pricing, provides the opportunity for astute managers to significantly reduce their expenditure and Cost of Production during 2014. The challenge is to make considered decisions based on real data, and not to be influenced by those with unrealistic expectations and deep pockets.