Nutrient Supply at Llysun
Detailed soil tests were pulled on the farm in the spring to determine deficiencies and inform recommendations. These tests analysed all the major cations and a range of micronutrients as detailed in an example of the results below.
The two fields which were selected for the trial had common themes, both having low levels of the micronutrients Boron & Zinc. These two elements play a vital role in the transporting of Calcium into the plant and therefore influence cell structure and the health and yield of the plant.
The main difference between the two fields was that one had pH and Calcium results below optimum. Both fields had slightly high Magnesium which will affect soil structure, this can however be rebalanced by using Calcium based Lime and fertilisers.
Nutrient recommendations for the two fields were therefore based around supplying Calcium, Boron & Zinc. Granulated lime plus Boron and Zinc was applied to the low pH field and Calcium Sulphate plus Boron and Zinc being used where no pH adjustment was required. Both application rates supplying 0.85 kg/ha of Boron & Zinc.
The difficult growing conditions of the 2018 season made it difficult to measure grass to monitor yield. Therefore, tissue sample were taken to monitor uptake of nutrient’s applied.
Boron levels in the Lime treated part of the fields were 10.2 mg/kg, moving this element from a low/deficient level to what is regarded as normal. The control result was 6.02 mg/kg. The results below for the treated field show a good balance of a wide range of nutrients at that time of the season. Zinc levels were also significantly lifted by approximately 20%.
The field which was treated with the Calcium Sulphate showed similar results compared to the control in relation to Boron and Zinc. It was also noticeable the response to Sulphur. The tissue samples showed a significant shift in the N:S ratio.
DAILY LIVEWEIGHT GAIN OF LAMBS INCREASES AS FEED N:S RATIO IMPROVES
Source: Rendig and Weir, J. Anim. Sci. 16(2)
The graph above illustrates how important the use of Sulphur is in grass based systems. The improved DLWG and known benefits of improved feed quality of conserved forage in terms of D Value, protein and digestibility cannot be ignored this element needs including in all fertiliser planning on farm as it is often the missing link in relation to quality grass and conserved forage.
Summary
When soil testing it shows how important it is to analyse for more than the basic pH,P,K,Mg as the test results above show that there are potentially more limiting elements that the big 3 macronutrients.
Soil analysis should include the important secondaries as well Calcium and Sodium being two of the most important. Ensure cation exchange capacity (CEC) of the farms soils is know when undertaking analysis as this will help inform of deficiencies or excesses, which will provide the right information for the types of fertiliser required. The CEC of soils varies according the clay %, the type of clay, soil pH and amount of organic matter. Generally, sandy soils has a very low CEC whilst clay soils has a higher CEC.
Ensure that any analysis done on farm helps inform fertiliser buying decisions not price as it may not be suitable for the soil or crop. Make sure the basics are corrected first - LIME! Before any fertiliser is bought or spread.