SAP Analysis…What We’ve Learned and Observed!

Sap Analysis is way to measurement nutrient levels and balance during the growing season. Sap analysis indicates what is happening in the blood of the plant. A sample is collected in two parts, a sample of old mature leaves as well as a sample of new fully developed leaves. This constitutes one sample. For the last five growing seasons many of CSI’s growers have been using SAP Analysis to improve overall plant health. SAP testing alleviates the need for guessing at what nutrients plants need, or counting solely on a soil test to determine what to apply. The benefit is we can fine tune fertility applications based on what the plant says it needs…not what we think it needs.

Having balanced and sufficient mineral nutrition is imperative to fully achieve the true potential of any plant.

There have been some very interesting revelations. One is that of Nitrogen; Lo and behold the wrong form and the wrong timing have been shown in most samples. Excessive Nitrogen in a plant guarantees insect and/or disease problems. In the case of excess Nitrates we see a direct correlation to reduced sugar content (Brix) and increased insect pressure.

SAP Analysis is the best way to monitor Nitrogen levels as it measures Nitrates, Ammonium and Total Nitrogen. This is particularly helpful specifically managing Nitrates as it is well understood excessive nitrates in plants reduces Brix which increases insect pressure. They also hold off the reproductive stage, as the reproductive form of Nitrogen is Ammonium. Excessive Nitrates cause long leggy plants; converting them over to Ammonium in the soil by microbes, and over to proteins in the plant will reduce insect pressure and allow the plant to begin its reproductive stage.

Protein synthesis in a plant is the conversion of the form of Nitrogen coming into the plant (Nitrates or Ammonium) and converting it to protein. This require requires Nitrogen, Sulfur, Magnesium and Molybdenum at optimum levels. Through SAP analysis we can monitor the correct forms of N and maintain optimum levels of the other three nutrients in the SAP to ensure this happens. Magnesium is rarely deficient, however in many systems Sulfur and Molybdenum are. This is easily addressed with foliar applications. In 2018, we observed many growers SAP results indicating excessive Nitrates in their crop also had a correlating Molybdenum deficiency. Adding 2-4 oz of a 3% Mo product per acre in a foliar, increased Mo levels to optimum, and consequently the Nitrate levels reduced significantly converting the Nitrogen over to protein. This is significant in any cropping system especially when going into reproduction/blossom.

The majority of the SAP analysis through CSI have been on Blueberries, with Corn and Soybeans following closely behind. In particular cultivars of blueberries, we have observed drastic differences in their ability to take up specific nutrients. One such instance is the Elliot variety. This variety doesn’t seem to take up Manganese (Mn) like other varieties. As we learned from Mulder’s Chart and SAP Analysis observation, Mn is the key to Potassium flow in the plant ultimately sizing (cell expansion) of the fruit, seed or ear. Ironically the Elliot variety doesn’t size like some of the other cultivars. A few growers have focused on increasing Mn foliar on this variety to determine if this would increase overall size. After one dismal weather season 2018 and a good season (2019) this experiment is inconclusive at this point.

The other big challenge in any cropping system is Calcium uptake. We know and have observed a direct correlation between Boron and Calcium uptake. If there is a Boron deficiency in the SAP, Ca levels will not reach the optimum range. Similar to the response with Mo, getting Boron levels in optimum range through foliar feeding allowed adequate Calcium into the plant providing the foundation for cell division. This is critical from growth through the reproductive stage as every root, shoot and the embryo of every fruit, cobb, vegetable and seed head uses copious amounts of Ca to build cell walls. Lack of Ca will certainly lead to weak cell walls and fungal problems. One other observation with respect to Ca is the situation where excessive Potassium can antagonize Ca uptake in the plant. In SAP testing the K:Ca ratio is another area that must be closely monitored. From a crop management standpoint, it is important to realize these nutrient interactions exist, so when applying nutrients to the soil or foliage be cognizant of timing and interactions. Applying excessive Potassium during the growth or bloom stage may cause problems with the “Blossom.” A weak blossom doesn’t attract pollinators (low Brix), is susceptible to insect pests, and leads to an array of bacterial and fungal diseases of the fruit, vegetable or grain.

The message here is SAP analysis is a tool to better manage a crop for nutrient balance, density, quality and yield. It stands to reason, SAP testing could save $$$ on fertilizers that don’t need to be applied. Consider SAP analysis for your operation.

NOTE: All SAP testing is completed at NovaCropControl in the Netherlands. Crop Health Labs, in Ohio, is a logistics company to get the samples there in a timely fashion. As such there are special labels, sampling instructions, packaging and shipping requirements to ensure the samples arrive in good condition. Turnaround times on samples is generally 5-7 days. CSI charges $75 per SAP Analysis set (young and old leaves) which includes interpretation (what to do with the information!) Please do not send samples to CSI, they must be shipped directly to Crop Health Labs, but don’t send them without contacting CSI first as labels must be preordered. For more information about SAP Analysis feel free to give us a call.