Using Plant Analysis to Monitor Crop Requirements In Season

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Plant tissue analysis is generally known as a tool for diagnosis of nutrient deficiencies. Unfortunately, crop yield can already be affected by the time visual symptoms of nutrient deficiencies are present. Monitoring nutrient concentrations on a regular basis throughout the growing season provides multiple opportunities to evaluate the plant’s nutritional condition to predict and “head off” nutrient deficiencies or identify “Hidden Hungers” that rob our crops of yield and quality. However, it is also an excellent tool to monitor and fine-tune crop nutrient supply during the growing season. For this reason we have developed our Plant Monitoring Program,(PMP)

This type of monitoring of the nutrient status of traditionally high-value vegetable and fruit crops with plant tissue analysis is common. With current commodity and fertilizer prices,plant tissue monitoring has a greater economic potential to help fine-tune fertilizer nutrient programs for row crops, as long as a good soil testing and fertility program is already in place.

Analyzing a plant tissue sample provides an evaluation of a crops' nutrient status at the time the sample is taken. Soil physical and fertility status as well as weather conditions the crop has experienced up to the time of sampling may have influenced plant nutrient levels. However, a plant tissue analysis cannot be used to reliably predict whether nutrient supplyand uptake will be adequate after the sample is taken. A plant’s nutrient demand changes quickly in-season as it goes from one stage of growth to another. A plant that was sufficientin the vegetative stage may become deficient in a nutrient as it transitions into the reproductive stage.

Crop demand also will change nutrient requirements year-to-year and field-tofield. A crop that has set up to produce huge yield potential may run out of nutrient supply simply because of the demand that it places on the soil and the soils ability to supply certain nutrients. A monitoring program will predict this and allow the grower to respond to that nutrient before it becomes yield limiting. In some years a soil may not have the potential to finish those huge crops.

A plant analysis-monitoring program involves taking samples at multiple times during the growing season and accurately identifying the stage of growth so that we can match it to our data base of ranges. Individual tests results are evaluated for deficiencies, but particularly for nutrient trends over time. One nutrient may initially be sufficient, then trend low due toavailability or demand that the crop is putting on the soil reserves.

If a nutrient need is identified, the corresponding question is whether an in-season application will effectively and economically correct the problem. If a correction is going to be effective it has to happen early in-season and it must happen before the nutrient reaches critical thresholds. Once an element reaches these critical thresholds it is difficult to get a response. Keep in mind when using a monitoring program your largest crop will run out of nutrients the quickest. A poor or low tissue test does not always mean a poor crop; it usually means there is a lot of demand on nutrient supply because the crop is using the nutrients. In other words your best crop may have the poorest tissue test. Just make sure you identify this and respond with correctives before it is too late.

A plant analysis-monitoring program can help identify nutrient management needs and opportunities throughout the season before they become yield and quality limiting. However, just asimportant, it can be a confirmation that a good soil fertility program is in place and that little adjustment is needed.

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