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With commodity prices continuing to be relatively weak every opportunity to increase the efficiency of use of inputs should be addressed. One such opportunity was the theme of last weeks HGCA R & D conference Precision Agriculture.

Many aspects of this approach were presented and the same questions raised which were fundamentally around what is the return on the investment that can be expected. This is always a difficult sum as every farm will be slightly different e.g. with regards to variable rate fertilizer, the return will depend on the inherent variability of the soil.

The first indication of variability is the yield map as after all this is the effect of what has gone before. The key then is to start to look as what has been the main cause of this variability. One of the causes is likely to be variable soil nitrogen supply as this is one of the main drivers of yield. Therefore an area to explore further which was covered at the conference last week is the nitrogen fertilizer application technique. Uniform nitrogen applications are still the norm, but a rapidly expanding method is variable rate applications.

By adopting this approach the Yara N Sensor has been shown to deliver, on average (from over 150 trials), an extra 3-4 % yield of wheat or oilseed with no additional fertilizer used. The most recent trials showed a 7% yield increase with 12% less nitrogen used, in addition to improving combine performance by 10-20%. Various other systems are now available either based on satellite images or tractor mounted sensors but they are more restricted on the crops they can be used on and they are not ‘real time’ solutions.

For further details contact ian.matts@yara.com  

The principle behind this new technique  is to target applications of nutrients in a band just below the seed at drilling (approximately 2”). As germination begins the newly emerging roots grow into the nutrient band which supplies the nitrogen and phosphate required for early autumn growth as the seed reserves are exhausted and reliance on soil reserves takes over. The concept is an accepted and well established principle in higher value crops such as potatoes, cauliflower and onions but in oilseeds very little data is available to endorse the theory. 

Theoretically, this concept should allow low rates to be applied to the targeted area, which would be equivalent to a typical broadcast  application rate of approximately three times the actual rate applied (depending on the spread of applied fertilizer and crop row spacing).  Therefore banding 10 kgN/ha  at drilling should be equivalent to the plants receiving 30 kgN/ha surface broadcast due to the increased efficiency of uptake and utilization.

Yara are including this technique in its 2009 trials programme  to investigate the impact of banding on required dose rates.

With very little UK data to be able to base a recommendation on, the grower needs to consider what is the background to moving to this technique. It is typically one of two:

1. To use the technique as a Starter Fertilizer. This option is based around placing fertilizer to improve the root system that then enables the establishing crop to use either soil nutrients or subsequent fertilizer application more efficiently. Typically here the grower will be applying approximately 10 kgN/ha in the band which equates to the NVZ closed period NMax of 30kgN/ha. Along with the nitrogen, 13- 20 kg P2O5 is applied which is equivalent to a 40-60 kg P2O5/ha broadcast application. Further applications of phosphate must be considered within the rotation in view of soil reserves and crop offtakes

2. To maintain NVZ compliance where higher rates of nitrogen are required. The oilseed crop requires more nitrogen in the autumn than most other combinable crops, with applications giving good returns. Yara  has  trials spanning over 30 years looking into the optimum rates of autumn nitrogen for the oilseed crop. Optimum rates are typically in the region of 40-50 kgN/ha (depending on the actual N price and OSR value). Actual rates also depend on soil type and soil conditions at drilling. Other independent work has also shown optimum rates to be in the order of 50 kgN/ha which is clearly higher than the NVZ NMax rate of 30kgN/ha. By banding fertilizer the aim is to achieve this same response without being non compliant. In such a scenario the farmer needs to be banding an equivalent  broadcast application of 20 kgN/ha.

With both the options above low application rates are required to prevent work rates being compromised. When managing these low application rates fertilizer quality is also a key ingredient – Yara liquid fertilizers are clear solutions – not suspensions - being formulated from the best quality ingredients. Whichever the option chosen the aim is to get the best autumn establishment possible which will deliver a high yielding crop in 2010. This year could be very similar to last year where the August rains left soils much colder giving very slow crop establishment. In such soil conditions (wet and cold) phosphate availability maybe compromised and thus the banded phosphate could well give good benefits.

Other considerations in developing the nutritional strategy for the 2009/10 oilseed crop is the addition of boron. Boron is also an important nutrient for oilseed crops in the autumn. Where severe autumn weather conditions might restrict field operations it may be beneficial to include YaraVita Bortrac 150 at 3 l/ha in the banded mix to ensure it is applied. If not applied with the banding application this can be applied as a foliar application with a fungicide. Yara trials have given an 11% yield benefit when Boron is applied during the growing season.