Understanding Soil Fertility
In the last blog, I gave you a website to visit designed to help you understand soil test report recommendations. I hope you found it useful. Interpreting a soil test report is not difficult but it does take practice. I refer to the soil test as the report card. Problems can be detected before they occur if you know what to look for. I would like to help you do that, so if you have questions I will make myself available to come to your locations to assist you. In this blog we will discuss alternative nutrient sources, the pros and cons of animal waste use and dry fertilizer vs liquid fertilizer.
Animal Waste and By-Product Use
In the Coastal Plain many farmers use alternative nutrient sources to grow crops. Animal waste contains every nutrient that a plant needs to grow and livestock producers are blessed to have a nutrient source they could either use or sell. By-product materials may also provide an economical source of nutrition. Although waste material are sometimes economical to use problems can occur from repetitive use.
Animal waste contain the following nutrients: N,P,K,S,Mg,Ca,Mn,Zn,B and Cu. By-Product materials generated off the farm contain some of the nutrients mentioned but may contain other elements such as Pb, Cd and Ar. One of the problems with waste products is that nutrient concentration is highly variable on a dry/ton basis. Samples should be taken properly for every waste source and sent to an accredited lab for analysis. Agronomic rates can then be determined for land application. Soil test can be your report card to determine if toxic levels are accumulating in the soil and if so, land application should cease.
Peanuts can be used as an example of a crop sensitive to heavy metals. Split stems can occur when soil test index levels of Zn reach 300 or higher. Plant death will occur when pH is low and Zn index levels approach 500 or higher. When growing peanuts never allow index levels to climb to a harmful level. NC has set toxic levels for other row crops at a 2500 index for Zn and Cu.
Remind growers that use waste products that supplemental fertilization with commercial fertilizer is very important. Normally when waste applications occur, more material is delivered from the rear of the spreader than on each side. Also buffer zones restrict application across an entire field. Distribution problems show when the crop starts growing. Weeds, can become an issue when using waste materials but that’s for another story.
The following pictures show toxicity symptoms and distribution problems
Toxicity Symptoms in Peanuts
Toxicity Symptoms in Soybeans
Dry vs Liquid Fertilizer
Which is better? Is there a better way? There are several answers to this question and depending upon where you are in the United States you will get different answers. Most University Specialists in the southeast will tell you not to abandon your dry fertilizer program. I tend to agree with this philosophy particularly when applying potassium and managing soils with low to medium soil test index levels. However, I don’t think we should be so naive to think there are not other programs that could work if nutrient reserves are high.
Nutrition is a balancing act. Products such as our Agri-Pop look very promising when applied in-furrow to satisfy early crop needs, however it should never be promoted as a material to last all season or to replace broadcast fertilizer. There is a role for both fertilizer systems but they should be matched together to maintain nutrient reserves in the soil and promote high yields.