INTRODUCTION - Plant Monitoring BMP
Once we have tested the soils and have an idea as to what nutrients are available in the soil, it then necessary to assess which nutrients are being taken up by the plant. Remember, just because it is in the soil does not mean it will be in the plant. Often nutrients are tied up or simply not transferred to the plant due to other limitations. Leaf tissue and sap testing are a simple process which is likened to a blood test for a human being. It is analysing the nutrients in the sap stream at a point in time.
Tissue testing has been used around the world for 30 years and has bulk of data to back up results. Sap testing is a newer process and has been highly promoted by various labs as well. To obtain a detailed analysis it is essential to send a sample to a reputable laboratory. We recommend (EAL) Environmental Analytical Laboratories at Lismore.
Plant monitoring is a term we use for assessing the condition of the plant (pasture or crop) during its growth phase. This begins from establishment phase and continues through tillering, vegetative phase into seed set. Plants require different amounts of nutrients at each specific growth phase and so nutrients need to be spoon fed to plants to ensure optimum production. The most common method of assessing the phase of the plant is to use the ZADOK reference.
In Paddock Test
A basic analysis can be carried out by good agronomists on site in the paddock to assess Brix (total sugars), nitrate levels, Potassium levels, and pH levels. A number of samples need to be collected from the paddock, crushed and squeezed to gather a sap sample. The sap sample can then be quickly analysed using:
- The Brix level or percentage sugar is measured with a refractometer, while
- The sap pH is measured with a pH meter
- The sap nitrate is measured with a nitrate meter and
- The sap potassium meter is used to measure potassium levels.
This methodology is used as a guide to assess the health of the plant in the paddock.
Full Laboratory Analysis
This analysis is very accurate and essential for serious farmers and graziers who are able to apply nutrients during the crop growth phases. The analysis would include: Example leaf test_
- Nitrogen
- Phosphorous
- Potassium
- Calcium
- Magnesium
- Sulphur
- Manganese
- Copper
- Zinc
- Molybdenum
And any key issues you have noted on your original soil test.
May include:
- Yield monitoring
- Leaf or tissue testing
- Sap testing
- Feed Budgeting
LEGUME MONITORING
A plant monitoring bmp will need to monitor the establishment of legumes and the success of the inoculation program. Remember all legumes require inoculation with the correct rhyzobium (strain of bacteria) for that species. In some situations an established strain may invade the plant roots to establish inoculation. If this is the case, separate external inoculation is not necessary.
To check inoculation, dig out a plant root and check for root nodules. The presence of root nodules will demonstrate the soil has correct rhyzobia. However, the nodules will need to be sliced in half to check if they are fixing nitrogen. If the nodules are pink inside, they are fixing nitrogen.
This page will be updated as necessary. For more information about testing protocols and to send samples to EAL, please contact 0438 395 255. The GBP Qld office can send you a complete kit.