Plant Testing for Agriculture
Plant materials can be tested for mineral nutrients or feed quality. Plant nutrient levels are valuable to identify nutrient deficiency or toxicity and to monitor the fertiliser programme.
About this Testing
Why Test Plants
Soil and herbage analyses help pastoral farmers and their advisers choose the best fertiliser programme. They also highlight mineral imbalances that might be affecting the health of pasture or animals that feed on it.
Herbage tests of pasture complement soil tests and allow important trace nutrients like cobalt, selenium, copper and iodine to be adjusted for improved animal health. Using both herbage and soil testing will provide a better overall picture of the farm nutrient status for an improved fertiliser programme.
As an independent lab, we leave the fertiliser recommendations to competent advisers who know the farm and the farmer's objectives.
What Tests to Order
- For pasture, the Mixed Pasture Profile analysis is commonly selected and this contains a Basic Plant Profile with added cobalt, molybdenum and selenium tests.
- The Basic Plant Profile includes analysis of nitrogen, phosphorus, potassium, sulphur, calcium, magnesium, sodium, iron, manganese, zinc, copper and boron.
- The Mixed Pasture Profile, which can be taken at any time of the year, includes a full mixed pasture test with added chloride, crude protein (CP), digestibility and metabolisable energy (ME).
- The Animal Dietary Mineral Balance (ADMB) Report can be requested on all Mixed Pasture Profile tests. This report shows the animal requirements and dietary intake per nutrient for a specific livestock class. Ask for the ADMB Report and supply details of the animals being fed.
Example Extended Feed Report with requested Animal Dietary Mineral Balance (ADMB) Report
Example Pasture Feed Report
Other pasture test options are included in the Services Offered Pasture Feed Quality Analysis.
Forage crops such as kale, triticale, fodder beet, lucerne and oats can also be analysed for mineral content. For example, as an animal feed crop, kale would be given a Basic Plant Profile with added cobalt, molybdenum and selenium.
Forage crops can also be tested for feed quality where the digestibility, crude protein, fibre levels, soluble sugars, starch, metabolisable energy and dry matter levels are analysed and this is discussed under Pasture & Feed Forage Quality
Nitrate Toxicity and Iodine tests can also be requested if you wanted to test for nitrate poisoning or Iodine levels.
Pasture Feed Quality with Mineral Analysis [Extended Feed Profile]
There will be times when you need a complete picture of your pasture, especially when metabolic disorders are an issue and you're still supplementing pasture with other feeds. Hill Laboratories provides a comprehensive herbage analysis, which combines the Mixed Pasture Profile with the Feed Profile. This profile is called an Extended Feed Profile.
The Extended Feed Profile includes analysis of: nitrogen, phosphorus, potassium, sulphur, calcium, magnesium, sodium, iron, manganese, zinc, copper, boron, chloride, dry matter, crude protein, ash, acid detergent fibre (ADF), neutral detergent fibre (NDF), soluble sugars, starch, metabolisable energy (ME) and digestibility.
To determine why your pasture is not growing so well, a clover-only sample is recommended. Healthy clover is the main source of nitrogen for pasture growth and clover develops mineral deficiencies before problems appear in grass.
Using clean scissors sample 100 clover leaves with stems, selecting from small, stunted plants or plants with unusual leaf colour. One clover-only sample per farm, from the poorest growing part of the farm, is usually sufficient. Request a Basic Plant Profile with added molybdenum test for the clover sample.
Stock being fed annual ryegrass can be susceptible to nitrate poisoning. You can ask Hill Laboratories to add a nitrate test to any of the above pasture profiles. Or if you're concerned that your pasture might be deficient in iodine, then we can analyse this mineral too.
Taking a Sample
For agriculture samples, collect 500g of actively growing herbage tissue from across each main grazing area. Using clean shears take 20 small handfuls of herbage in a diagonal line across the sample area and combine into one plant sample bag. To help avoid soil contamination, cut at grazing height (about 5 cm from the ground). Avoid dung and urine spots and recently grazed pastures and do not sample within three months of applying fertiliser or lime. Traces of soil or chemicals (such as drench) on your hands will contaminate test results.
To reduce the risk of sample contamination, Hill Laboratories has available Pasture Shears with side-walls to hold the pasture sample for transfer to the sample bag. These pasture shears reduce the risk of sample contamination and can be purchased from the laboratory . Sampling at the same time of year in the same way will give better nutrient monitoring.
How to Order a Test
Hill Laboratories suggests that you use a consultant or fertiliser specialist to oversee your soil and plant testing program. However, you can order a complimentary Soil & Plant Test Kit (including sample bags, a courier bag, instructions and a request form) from the laboratory.
Guides and Supporting Information
Freephone 0508 HILL LAB (44 555 22) or email Ag.CSM@hill-labs.co.nz