US - Producers thinking about pasture improvement should start by testing the soil, says Jim Camberato, Purdue Extension soil fertility specialist.
"Establishing proper pH and adequate nutrient levels in the root zone is important for the health and productivity of the plants growing there," he said.
The first step in soil testing is collecting samples. Mr Camberato recommends that farmers use a soil probe to take 15-20 core specimens from a sampling area encompassing no more than 15-20 acres. Each sampling area should be determined on the basis of common characteristics - including soil type, location and management history.
"Soil analysis and lime and fertiliser recommendations are only as good as the samples," Mr Camberato said. "Do not skimp on the number of cores or increase the size of the sample area represented."
Soil core samples should measure 1 inch in diameter and 4 inches deep in established pastures and 8 inches deep for soils that are to be planted. Producers should crush and mix the soil cores well in a clean plastic container and send a 1-pint sample to a commercial laboratory for nutrient testing.
Camberato said it is important for farmers to get a basic analysis of pH, organic matter, cation exchange capacity, plant available phosphorus, potassium, calcium and magnesium. Micronutrient analysis is not usually necessary for pasture sampling. Mr Camberato recommends that producers go to the Purdue Extension website to find a list of certified soil testing labs.
Certified soil testing labs will usually report recommendations from the analysis for an additional fee. Farmers who are unable to interpret the analysis themselves can consult Purdue Extension's Forage Field Guide or ask an expert for help, Mr Camberato said.
Based on the soil test results, Mr Camberato said producers may need to apply phosphorus or potassium in-season or shortly before seeding. If a pasture's pH level is unfavourable, lime should be applied to the pasture as soon as possible.
Mr Camberato said now may be the best time for fertilising worn-down pastures.
"Fertiliser prices are relatively low this season, so it may be a good time to take care of pastures that have low P and K levels," he said.
He had special advice for producers who plan to establish new pastures. "It is beneficial to establish adequate pH levels with lime and adequate phosphorus and potassium levels with fertiliser before seeding so that as much of the root zone can be affected as possible," he said.
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