In a previous post I have addressed the difference between zone sampling and grid sampling. From that post one could gather that I am not a big proponent of zone sampling. The reason why is because when establishing the zones to be sampled the method used to establish the zones, e.g., by soil type or Veris data, is not necessarily related to the level of nutrient being tested. As a consequence, variability of nutrient levels within the zone can be just as high as it is within the entire field. If this is the case, why would I want to reduce the number of samples I pull from a field? Am I not getting a less accurate result? Continue reading
Yesterday, I was talking with a company agronomist about their humic acid product and he was saying that the humic acid increased fertilizer efficiency enough that you could cut your fertilizer rates back by 20% and see no detrimental effect.
At the center of this claim is the fact that when fertilizer is broadcast, in the case of Phosphorous, approximately only 20% of the material is available to the plant in the year of application.The company agronomist claims that his product increases the percent available in the first year from 20% to about 50%, thereby allowing for reduced rates.
I asked him if using reduced rates would pull the soil levels down over time and he answered with a very confident “no”, but when we delved into the topic further, he could not explain how this would not happen.
I presented this agronomist with the scenario that if I applied 60 lbs. of P2O5 and the plant removed 80 lbs. of P2O5, where did the other 20 lbs. come from? He could not answer this simple question.
Of course it’s very obvious where the plant obtained the other 20 lbs. of nutrient; it came from the soils reserves. So if it came from the soils reserves, the soil test level will drop over time, or in other words, the soil is being mined of that nutrient.
I think it’s very important that people understand exactly what “efficiency” means. When “industry experts” talk about fertilizer efficiency, they are not talking about reducing the amount of nutrient the plant needs in order to produce a crop. Rather, they are talking about the portion of applied product that remains available to the crop in the year of application.
The take home message of all this is that if you apply less nutrient than the plant removes, soil test levels will fall and eventually yield will be adversely affected.
One of the most popular methods of evaluating new products in the field is with side-by-side test plots. The reason is because a side-by-side plot is easy to set up and easy to obtain results at harvest. But as we all know, quick and easy is not always the best path to take. This is certainly true with side-by-side comparisons. I’ll explain why. Continue reading
With the overabundance of rain recently, a lot of corn is beginning to show signs of nitrogen deficiency. Because of this, there have been a lot of questions concerning foliar nitrogen applications. In particular, there is a lot of interest in the “controlled release” forms of liquid nitrogen that are being sold in the marketplace. The biggest question is whether or not these products perform as advertised. I’ve addressed this issue in a previous post and have come to the conclusion that buyer should beware. But, this is my opinion (based upon agronomic principles), so what does the research say? It’s a fair question so I’m providing a summary of the reasearch along with links to the original source. Continue reading
With the recent explosion of foliar applied nitrogen products in the marketplace, I often field questions regarding whether or not these products actually work or are they just another in an endless line of snake-oil products. This is a fair question; especially since the products are not cheap to buy and/or apply, but if they do perform as advertised they have the potential for a nice return on investment. Continue reading
With all the discussion about zone sampling versus grid sampling between advocates of both systems, I think it’s absolutely essential to know the benefits and shortcomings of each system.
There is no doubt that zone sampling saves money versus grid sampling. With grid sampling, in order to ensure an acceptable degree of accuracy, a lot of samples need to be pulled and analyzed which drives up costs. Conversely, zone sampling reduces costs because it is assumed that given areas within a field, as one poster in a thread below so eloquently put it, are homogeneous. In other words, the variance in pH and nutrient levels are minimal so these zones can be sampled as a composite, thus reducing costs. But is this true? Are zones homogeneous enough that we can in fact reduce sampling frequency in order to reduce costs? I have found that the answer to that question is usually a resounding no. Here’s why….. Continue reading