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Soil Depletion The Ignored Crises

Bob Wilt

Originally Published in ACRES Magazine April 22 Edition.


Have you noticed how over the years growers are applying more fertilizers, fungicides, and insecticides and getting less crop response than 20 years ago? I can remember until 1996 I did not need to use fungicides and insecticides on my conventional Blueberries. I can also remember in the 80's growing wheat with no fungicides or insecticides and minimal fertilizers. I can also remember in the 70's growers planting wheat or sweet corn on freshly cleared ground in western Oregon and not using any fertilizer or pesticides including herbicides for the first several years and getting average or better crops. Then after several years those same growers would have to start applying salt fertilizers to get the same yield and in the following years using more and more. Then after about 15 years they would need to start using insecticides and fungicides and as time goes on were depending on them more. 


As a consultant I have had clients come into my office and tell me that they are applying 150% to 200% more fertilizer to their crops now to get the same crop response that they did ten to fifteen years ago and buying more pesticides at the same time. I have had numerous Blueberry growers tell me that after about fifteen years a berry planting will fall off the edge and start to have more disease and insect problems while the yields are diminishing and that they are ready to pull them out. I, too, experienced this with my Blueberries. After doing some research and switching to regenerative practices which included addressing the remineralization and revitalizing of the soil and soil biology, I have revived those plantings, and they are producing good yields with high brix and little if any disease or insects, In fact, I do not use any insecticides or fungicides on any of my berry fields. Some of these plants are as old as 48 years and are doing better now than 15 years ago. 


What has happened in the last 40 to 60 years? Very simply put, depletion of our soils. When I say soil depletion, I am not so much focused on N-P-K, even though N-P-K has its place, rather the biological components that are found in fertile soil that makes a plant grow healthy and vibrant without disease and insects. These items are soil carbon, soil biology, and available minerals in a proper balance. Without these items it is impossible to grow a crop that is nutrient dense or in these days without fungicides and insecticides. 


The question that then comes to mind is what is causing this depletion? It is the over and improper use of salt fertilizers, pesticides, not replacing soil carbon, not replacing minerals that are being hauled off with the harvested crops or from leaching or volatilization and improper tillage. Then as a result the need for fungicides and insecticides that further damage the soil carbon, and soil biology is increased. This creates a vicious circle, the more salt fertilizers and pesticides that are applied the sicker the soil and the sicker the soil the more the perceived need for salt fertilizers and pesticides. 


Salt fertilizers will oxidize soil carbon and kill soil biology. The worst culprit being anhydrous ammonia. When this happens, soil carbon is turned into CO2 and microbial populations including bacteria, fungi, and protozoa are destroyed and minerals can and will be leached from the root zone. This can go on for as long as 20 to 30 years before we start visually seeing a deterioration of our soils which leads to degraded crop health and degraded yields. Which in turn leads to more use of pesticides which perpetuates the downward spiral of soil health. This is where most of our soil is today. It has happened slowly and consistently across our country since the mid 1940's with the introduction of salt fertilizers and the N-P-K philosophy. 


Many growers do not understand the true importance of soil carbon, biology, or minerals except for N-P-K. Soil carbon is necessary for several things such as water retention, mineral retention, and food and shelter for microbes. Soil microbes are necessary for digesting plant carbons, solubilizing all the necessary minerals for the plant, and fighting off soil borne diseases to name a few. All the solubilized minerals as many as 79 are food, energy, and contribute to the plant's immune system. It is these soil factions that will allow a plant to grow without disease, insects and approach its genetic potential. N-P-K alone will never get this done. 


With this being said, I think if the modern conventional grower is to survive in these times of low margin markets and increasing government regulations, he will need to learn how to incorporate regenerative practices into his management skills to where he has a hybrid toolbox of conventional and regenerative practices. In this way he not only holds the existing soil fertility in place but can turn the situation around and start improving the fertility. 


About nine years ago I decided to grow some black raspberries. In my research prior to planting, I discovered that black raspberries typically get a virus and after three crop cycles the grower usually pulls the crop and goes to something else. While visiting with a grower that had grown black raspberries all his life, I asked how long could his father grow a crop before taking them out? His answer was 18 to 20 years before they would become uneconomical. After hearing this I said to myself this is a soil depletion problem. 


When I planted the black raspberries, I amended the soil with a year of cover crop, some compost, a combination of lime and gypsum, and rock dust. Since then, every year I continue to add minerals. My fertility program includes plant derived fertilizers, humates, products from the ocean, and constantly adding biology in the form of inoculums. My goal is to replace anything that the crop is taking, maintaining, and improving the soil carbon, and encouraging the soil biology to thrive. The result of this effort is that this year was our sixth crop of black raspberries. Where other growers harvest about 4,000 pounds per acre the first year and go down to under 1,000 pounds by the third year. We started at 6,000 pounds per acre the first year and have maintained above 4,900 pounds every year. I am going into our 7Th harvest year and the plants look as good as in previous years. At this point it looks like we can continue to grow this crop for many years to come. This demonstrates that the life span of a perennial crop is functional to soil health and soil mineralization. 


When I decided to plant a planting of blackberries, I used the same preplant procedure of preloading the soil as I did with the black raspberries knowing that the soil needed help. This soil had been cleared and turned into farmland only 75 years ago but from soil testing I could tell it was depleted minerally and biologically. This would be considered from an agricultural point of view a young soil compared to most of the country, yet it was depleted. The previous history of this land before I started farming it was strictly a N-P-K fertility program. 


Since 2010 we have been invaded by an insect called Spotted Winged Drosophila commonly known as SWD. This insect will lay its eggs in ripening fruit or berries. Five days later the eggs hatch and you have worms in the fruit. Across the board there is a low tolerance for these worms in fruit and as a result, conventional and organic growers will spray appropriate insecticides every five to seven days from the time of color change to harvest. This means that fruit or berries can be sprayed four to six times prior to harvest. 


When we started to harvest the first crop of blackberries the first picking was within tolerance for SWD, but we could see signs of infestation. So, the next five pickings we applied an organic insecticide. The first pick was typical with good quality and an average brix of 14. The following pickings progressively had lower quality and lower brix. The last two pickings went as juice grade. The crop had run out of energy as the season progressed. The following winter we applied more amendments focusing on minerals and soil biology with the idea of raising fertility. When harvest came around this time, we harvested the first two pickings without SWD, and only the last picking went for juice grade. As with the year before again we amended the soil aggressively. The third-year harvest was quite different than the first two in those all six pickings there was no SWD. The first three pickings were very high-quality fruit (19 brix) and the last three pickings all went "A" grade with 14 to 15 brix. As you can see, as the soil health and fertility improved so did the quality of fruit and resistance to insects. This was also true of disease.

 

Most growers are facing a huge dilemma in that they are being pulled in multiple directions at the same time. They may and may not know how bad some of these practices are such as using anhydrous ammonia as a nitrogen source. They are working on tight if any margins and anhydrous is the cheapest source of nitrogen. Yet at the same time they are working themselves into a deeper and deeper hole because the soil is being depleted on an annual basis and the negative effects are now accelerating and showing that there are insect and disease pressures that were not here ten to twenty years ago. This is an indication of lack of soil and crop health, not a shortage of pesticides.


Another problem is most growers have not been properly educated on the importance and management of soil biology, soil carbon, and soil mineralization including all the needed minerals not just N-P-K. As time goes on growers are going to be forced through regulation and economics to learn how to utilize these principles. I have spoken with growers that are getting 220 to 240 bushels of corn to the acre using cover crops and no fertilizer and their yields are trending upward not downward without insecticides and fungicides.

 

It is well understood that regenerative farming takes more management and sometimes in the short run is more expensive than conventional farming. It is also these conventional short cuts that has put American soils in the sad condition that they are in today. For twenty years I have tried to do the right thing for my soil, sometimes costing more and taking more effort. For that commitment, the reward has been that I have raised the organic matter from an average of 2.25% to 6% and with a vibrant biological community and improved mineral content which allows me to grow high brix berries without insects or disease and have the reputation of some of the best tasting berries. Also, our berries test above average for nutrition. 


From over 50 years of farming experience and 10 years of consulting with growers all over the USA I have discovered that soil health is paramount to growing high yielding high quality crops without disease or insects. Many times, it will take twenty to fifty years to bring our soil to the breaking point which is where this country is today. Few growers today are around to know how good our soil was 50 or more years ago and are willing to accept the idea that this is as good as it gets. It is human nature to accept what you are doing if you do not know there is better. I have seen in the crops that I grow and food that I eat that when grown in healthy soils compared to most soils in this country, we have no idea of what good crops or good food is.

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