Production Pointers - Dr. Robert Mikkelsen

June 20, 2014 –
It is no surprise that high-yielding hay and forage can deplete the soil reserves of nutrients. A study from the University of Idaho estimated that 100 years of silage corn production will remove over 22 tons of nutrients/acre from the soil. This huge quantity is a reminder that it requires over $10/acre to recover the value of the nutrients exported in fresh silage corn, and over $50/acre for the nutrients removed inn grass hay harvest. It also explains why soils that historically had abundant nutrient supplies are becoming depleted where a regular program of nutrient replacement is not practiced.

June 10, 2014 –
A recent study from the University of Idaho reported on the quantity of potassium removed in their fields during forage harvest. They found that barley silage removed the greatest amount of K₂O (456 lbs/acre), followed by 385 lbs K₂O for corn silage, and 346 lb K₂O/acre for alfalfa. Soils with a sufficient K supply may take up more of this nutrient than is required for plant growth. However, the magnitude of nutrient during crop harvest removal clearly illustrates how soils can become depleted of K over time.

June 1, 2014 –
The total forage and silage yield largely determines the amount of nutrient removed from the soil during harvest. The tissue concentrations of several nutrients will drop as the hay gets more mature. Phosphorus concentrations are an exception, in that it does not change much over time. A recent study by the University of Idaho reported that for their growing conditions P removal was greatest with corn silage (116 lb P₂O₅/acre with 11 ton yield) and alfalfa at bud stage removed 84 lbs P₂O₅/acre at 8 tons/acre.

May 20, 2014 –
High-yielding alfalfa can be profitable to grow, but the cost of the nutrient depletion from the soil should not be forgotten. Estimates from the IPNI Nutrient Removal Calculator suggest that each ton of alfalfa removes 12 lb P₂O₅ and 49 lb K₂O. Alfalfa also removes large amounts of nitrogen, but this is primarily supplied through the Rhizobia bacteria on the roots.

May 10, 2014 –
In addition to producing hay for animal feed, corn silage also fills an important role in supplying forage. Wisconsin, California, and New York are the leading states in silage corn production. The IPNI Nutrient Removal Calculator estimates that corn silage production removes 3.1 lb P₂O₅/ton and 7.3 lb K₂O/ton from the soil at harvest. Productive corn silage fields in Wisconsin may produce 20 tons/acre, while in California yields regularly reach 30 tons/acre.

May 1, 2014 –
The importance of export markets for hay growers should not be ignored. West coast growers ship the largest amounts of hay to Japan, with a value over $340 million/yr. This country is followed by United Arab Emirates, Korea, China and Taiwan. These countries need plenty of premium-quality hay to feed their growing herds and flocks. Most of these countries have limited land or water resources and are not able to grow sufficient hay to meet their domestic feed requirements.

April 20, 2014 –
Hay and forage has traditionally been grown in close proximity to where the animals were fed. With the advent of inexpensive containerized shipping and new technology for bale compression, international hay trade is now commonplace. In the Western U.S. states, over 12% of the alfalfa is exported and over 30% of the grassy hay goes overseas. Only the best hay quality is acceptable for export buyers.

April 10, 2014 –
The importance of hay and forages is too often overlooked during discussions of agricultural production. Through years of drought and flood, animals still need to be fed and hay must still to be grown. In 2013, hay production in the U.S. was up 13 percent and the 58 million acres represented an increase of 4 percent over the previous year.

April 1, 2014 –
Starter fertilizer can be an excellent way to give crops a good early season “start”. This practice refers to the placement of fertilizer in a band either near the seed or with the seed rather than a specific type of fertilizer. Adding starter fertilizer for corn silage production often results in improved early season growth, increased yields, and earlier maturity. Positive responses to starter P fertilizer are most frequently observed in low-P soils and in cool spring conditions. However this practice is often recommended even in soils with optimum or higher concentrations of P. Band placement of P is also an environmentally beneficial practice because when placed beneath the soil surface, P is less susceptible to surface runoff with water then when left on the soil surface.

March 20, 2014 –
Consider banding with a starter fertilizer in situations where getting the crop off to a quick start is important. A starter fertilizer containing N, P and K is important in establishing a vigorous crop that can withstand adverse spring weather. Developing a strong root system and ground cover as quickly as possible is also important for erosion control.

March 10, 2014 –
The growth and yield of crops are largely influenced by their genetic potential and the environment in which they are grown. Maintaining an adequate supply of plant nutrients in the soil lets the plant convert the maximum amount of solar energy into biomass energy. Plants differ in their response to nutrient shortages, but stress frequently occurs without visible symptoms on the leaves, but with reduced harvests. Learn as much as you can about your crop’s requirements and then follow it up with soil and tissue testing as needed.

March 1, 2014 –
High yields generally come when good management is linked with good weather. Although climate is variable and weather is unpredictable, good management can be controlled. Proper management is based on a variety of field-specific objectives related to economic and environmental factors. There are many things we cannot control, so make sure to carefully manage the ones that can be controlled.

February 20, 2014 –
In discussions about using fertilizers and various plant nutrients, the entire purpose of using these materials is too frequently overlooked. All of the effort that goes into acquiring, transporting, applying, and managing these valuable resources is for the primary goal of growing healthy and abundant crops for humans and animals. Removing crop products from the field also extracts nutrients from the field. The harvested products may be used for things such as blue jeans, biodiesel, animal feed, or eaten directly by people. It becomes necessary to replenish the soil as the nutrient reservoir becomes gradually depleted.

February 10, 2014 –
We are familiar with the concept of preventative medicine, where health problems are avoided by good practices instead of curing sickness after they occur. This same concept applies to damage caused to crops by plant diseases and pests when adequate and balanced nutrition is lacking. New scientific studies are again confirming what farmers have known for many years about the link between plant health and nutrition. Healthy plants can generally withstand stress and attack better than plants that are already in poor condition. For example, recent work with corn has demonstrated the link between an adequate K supply and increased leaf thickness, stronger epidermal cells, and decreased leaf concentrations of sugars and amino acids. All of these factors lower the attractiveness of plants for pests, such a spider mites.

February 1, 2014 –
Sulfur is often considered a secondary essential element, but it is just as vital to plant productivity as nutrients such as N and P. Shortages of sulfur are increasingly showing up in the field as lost yield, chlorotic plants, and stunted growth. Not every soil and crop will require additions of sulfur, but don’t ignore the possibility that you might be running short.

January 20, 2014 –
Increased emphasis is being placed on using nutrients efficiently. Plant nutrients are an essential part of supporting high-yielding and profitable crop production. Avoiding wasted nutrients helps with the farm economics and also limits the chance for adverse environmental impacts. For example, considerable amounts of P can be lost from cultivated land with erosion during storms. Implementing soil conservation practices will preserve valuable topsoil as well as keep nutrients in the place where plants can use them.

January 10, 2014 –
The total amount of water that percolates below the crop root zone is a major factor in nitrate leaching from agricultural soils. Both percolation and nitrate leaching losses are usually greater when there is no growing crop in the field. As much as feasible, soil should be kept covered with a growing crop to prevent nitrate leaching losses.

January 1, 2014 –
Leaving the soil covered with a mulch can often be beneficial. A mulch covering increases the soil temperature during the winter and reduces the soil temperature during the summer. Mulches may temporarily slow the rate of soil warming during spring and early summer. By slowing down the evaporation from wet soil, a mulched soil may retain a considerable amount of water for the crop to use later in the season.

December 20, 2013 – Magnesium and Its Essential Role
Magnesium (Mg) has many essential roles in plants. This includes its role as an enzyme activator and a component of chlorophyll molecules. Magnesium is mobile in plants, so deficiency symptoms are first seen in older leaves. Root growth is also reduced when Mg is lacking, but these symptoms are not usually obvious. Plant and soil analysis should be used to establish the need for additional Mg. When Mg is lacking, there are many excellent sources of this important nutrient.

December 10, 2013 –
The concentration of nutrients in plant tissue can be a useful guide for diagnosing deficiency, sufficiency, or toxicity. Many factors influence plant nutrient concentrations including the plant part, the age, the species, and the soil nutrient supply. Work closely with your analytical laboratory to make sure the proper plant samples are taken to have useful results. When problem areas are seen in the field, plant samples should be taken from the area with poor growth and compared with samples of healthy plants growing in nearby areas.

December 1, 2013 – Adequate Calcium in Essential
A lack of calcium (Ca) is a problem in many acidic soils. Calcium (Ca) is just as essential as the macronutrients (N, P, K). Calcium is needed to form Ca pectate, which is found in the middle lamella of cell walls. When Ca enters the cell wall, it is irreversible and cannot be translocated to other parts of the plant. This means that plants must have an adequate supply of Ca throughout their entire growth cycle.

November 20, 2013 – High Yields have a Nutrient Cost
Crop yields have significantly increased in the last few decades in most parts of the world. Higher yields place a bigger drain on soil nutrient reserves and make maintenance of soil fertility a higher priority. Many soils in Western North America once contained abundant K due to the original geologic parent material. However after a century of crop growth and nutrient removal, there is now need to apply K fertilizer to these soils.

November 10, 2013 – Balanced Plant Nutrition in Fundamental
The concept of balanced nutrition implies that all the essential plant nutrients are in adequate concentration and proportion to meet the needs of the crop. Years of research and experience have repeatedly demonstrated that when one nutrient is lacking, none of the other nutrients is properly utilized. For example, the loss of nitrate through leaching is increased when crop growth is limited by a lack of P or K.

November 1, 2013 – Plant Nutrients are Primarily Inorganic
Plants use nutrients almost exclusively in the inorganic form. Although organic matter is an important reservoir for many nutrients, they are converted to inorganic ions before roots take them up. Additions of organic matter can be beneficial for improving the physical properties of soil, but the nutrients that are needed for plant growth are the same, regardless of their source.

October 20, 2013 –
Soil moisture is one of the controlling factors for supplying nutrients to plants. Nutrients most be dissolved in water before they can be taken up by roots. A soil may contain an adequate nutrient supply, but if there is insufficient water to dissolve and transport nutrients to the roots, then plant growth will be limited.

October 10, 2013 – Soil Acidity Pointers
Soil acidity is one of the most limiting factors for crop production in many parts of the world. Technically any soil with a pH below 7 can be considered as acidic, but crop growth does not usually suffer until pH drops below 5 or 6. The damage done to plants growing in acidic soils is not only directly related to pH, but includes several factors such as aluminum toxicity, possible lack of calcium (Ca) and magnesium (Mg), or micronutrient disorders.

October 1, 2013 – Measuring Efficiency
There is increasing emphasis on improving efficiency at all levels. This includes getting the most value from applied fertilizer. In addition to maximizing economic efficiency (or return on investment), it is also useful to keep track of partial factor productivity (such as bushels of grain per pound of N fertilizer). This is measured by measuring crop yield per unit of nutrient applied. Tracking this measure of efficiency helps you know if you are making progress over the years.

September 20, 2013 –
The economic benefit of fertilization generally focuses on increasing crop yield. However an adequate nutrient supply can also pay dividends by increasing crop quality. For example, adequate fertilization improves the solid content in potato and tomato. Balanced nutrition maintains the size of cotton fibers. Wheat and barley quality is maximized with careful nutrient management practices. Clearly, proper crop nutrition provides a variety of important benefits in addition to supporting high yields.

September 10, 2013 –
Farmers have many costs that are fixed and must be paid regardless of profit. These include expenses such as taxes, land, and machinery costs. As these fixed costs increase, the importance of optimum use of variable inputs, such as fertilizer and irrigation, to sustain profit margins grows even greater.

September 1, 2013 –
Since fertilizer and other agricultural inputs are a large part of farming costs, it is important to keep an eye on these expenses. The key to maintaining profitability is not merely cutting costs per acre, but lowering the cost per bushel or unit of crop production. The profit margin is the difference between the crop sale price and the cost of production. Adequate fertilization is a smart strategy for maximizing profits.

August 20, 2013 –
Planning for proper fertilizer use is complicated by fluctuations that cause the ratio of fertilizer costs to crop prices to frequently change. Additionally, there is uncertainty in annual weather conditions, pest pressures, etc. which can cause the achievable yield to rapidly change. Long-term business plans usually rely on maintaining a high level of soil fertility and productivity for the best economic returns. Farmers should carefully manage those factors that are in their control.

August 10, 2013 –
The fertilization rate that gives maximum profits depends on the ratio of the fertilizer price to the price of the crop. Fertilizer application pays for itself until the last pound of nutrients applied produces just enough harvested product to pay for itself. Profit-minded farmers need to keep their attention on the price ratio of fertilizer cost to crop price. Proper management is also needed to effectively deliver the nutrients to the plant and keep them in the rootzone.

August 1, 2013 –
Farmers and scientists have known for many decades that adequately nourished plants are more able to withstand diseases and better compete with weeds and insects. Soil testing helps ensure that an adequate supply of nutrients is available to the crop for quick canopy development. Healthy plants are better at withstanding pests and at shading weeds.

July 20, 2013 –
An adequate soil P supply allows plants to also use other nutrients efficiently. There are numerous examples to show that nitrate leaching losses from the root zone are increased when other nutrients are lacking. A shortage of any of the essential plant nutrients causes plant growth to suffer and impairs the plant’s ability to properly use all the other nutrients.

July 10, 2013 –
In soils that are low in available phosphorus, crop development is frequently slowed down. This often results in weak plant growth and reduced yields. In soils with a history of P application, fertilizer additions are largely geared to maintaining production by merely replacing the nutrients removed during harvest and by keeping soil test levels in the recommended zone.

July 1, 2013 –
Soil testing has been compared to a fuel gauge. If the soil “tank” is low in nutrients such as P or K, the test tells a farmer that it is time to replenish the nutrient supply. If the tank is full, there is the option of adding only the nutrients needed by the current crop or waiting another year or so before replenishing the soil nutrient reserve.

June 20, 2013 –
The acidifying effects of sulfuric acid on soil are immediate, while elemental S requires a period of time before the acidity is generated. Sulfuric acid application rates typically range from 0.5 to 2 ton/A. When using sulfuric acid, always make safety the first priority. Always be carefully trained before handling this material and use appropriate personal protective equipment for the task. Make sure that the proper handling equipment is used to prevent severe skin burns.

Perhaps urea-sulfuric fertilizer is a safer option for acidifying soil and irrigation water. Urea-sulfuric fertilizer largely eliminates the corrosive action of sulfuric acid on human tissue, but will immediately release the sulfuric acid when added to water.

June 10, 2013 –
A tell-tale sign of high bicarbonate irrigation water is the white scale that accumulates on emitters, pumps, and faucets. The typical treatment for this problem involves lowering the water pH to 6.5 or lower to remove the bicarbonate as carbon dioxide gas. A concentration of less than two milliequivalent per liter is recommended to keep calcium carbonate or lime from precipitating, which can plug emitters and microsprinklers.

June 1, 2013 –
A water test in the laboratory is the best way to evaluate if you have high concentrations of bicarbonates in your irrigation water. Knowledge of the bicarbonate content of the water helps you predict the “liming” value of the water. This lime build up can occur in the soil or appear as scale on irrigation equipment when bicarbonate reacts with soluble calcium. If the pH of the irrigation water is below 7.0, it probably is not a significant liming material, but at higher pH, a laboratory test is a good investment.

May 20, 2013 –
Sulfuric acid can be used for dropping the soil pH, which may increase the plant availability of P and certain micronutrients. In some conditions, irrigation water that contains elevated bicarbonate is treated with sulfuric acid to remove it as carbon dioxide gas. Irrigation water containing soluble bicarbonate reacts with calcium (Ca) to form lime. This Ca is no longer soluble or on the soil cation exchange sites to counteract the negative effects of sodium.

May 10, 2013 –
Addition of elemental S is the most common way to intentionally acidify the soil. Soil microbes convert (oxidize) elemental S to sulfuric acid. Chemically speaking, for every mole of S added, two moles of acid are produced by this microbial reaction. There are several excellent solid and fluid sources of S that can be used to acidify soils.

May 1, 2013 –
Additions of urea or ammonia-containing fertilizers to soil cause gradual soil acidification. When soil microbes convert ammonium to nitrate (NH₄⁺ to NO₃^-), hydrogen (acidity) is also produced. Some soils are able to withstand a drop in pH (well buffered), while poorly buffered soils can experience a drop in soil pH within a few years.

April 20, 2013 –
There are times when it is desirable to intentionally lower the soil pH. This is commonly done to improve nutrient solubility in alkaline conditions. It is also common when treating sodic soils or where irrigation water contains considerable bicarbonate. To lower the soil pH, elemental sulfur or sulfuric acid additions are the most common amendments. However, other excellent products are available in specific regions to lower soil pH.

April 10, 2013 –
In high-rainfall areas, water percolating through the soil carries soluble anions [such as chloride (Cl^-), nitrate (NO₃^-) and sulfate (SO₄^-2] with it. In order to keep a neutral electrical charge, soluble cations such as sodium, potassium, magnesium, and calcium are also leached. As these “basic cations” are leached from the surface soil, the “acidic cations” such as hydrogen and aluminum are left behind, causing the soil pH to decline.

April 1, 2013 –
All soils tend to become more acidic over time (ranging from several years to millions of years). Pure rainwater reacts with carbon dioxide in the atmosphere to form a dilute solution of carbonic acid before it lands on the soil. When fossil fuels are burned, they sometimes emit sulfur and N that can make rainwater even more acidic.