PRODUCERS SHOULD TAKE OPPORTUNITY TO ENHANCE FORAGE

by: Stephen B. Blezinger
Ph.D., PAS

Part 5

As we continue the discussion of how to make the most of the strong cattle markets the industry has been experiencing, we should expand on the sub-topic we started the last time; that of producing quality forages. Part 4 included an overview of producing quality hay but obviously there is much more to a quality forage base than just the hay produced. The plant base itself is the foundation of the pastures and forages that make up the majority of the animal's diet throughout the year. The better the quality (nutrient value, density) and quantity (pounds or tons produced per acre) the more pounds of beef that can subsequently be produced per acre.

So what are the opportunities for the producer to enhance the forage base of his pastures and hay fields? For the sake of this discussion assume we are only considering production of grasses and legumes, not actual row crops although these are options as well depending on the operation. One obvious thing that has to be pointed out initially is that unless some or all of the operation is irrigated, forage production, especially volume, is at the mercy of amounts and timing of rainfall. All the best laid plans as well as management tools are for naught if the moisture is not there. So this can be considered a qualifier for all of the following. That said, just as we focus on the nutrient source for the animals, the forages, in this part we'll spend some time focusing on the nutrient source for the forages themselves, the soil.

“You‘re not really a cattle producer, you are a grass farmer.” Or perhaps a legume farmer if your forage is alfalfa, clovers, etc. Most cattle producers have herd this statement. While your end product is beef or rather, a live animal, the main material used in producing that animal is the forage (generally grass) produced on the land. Through a variety of methods you harvest this grass, but for the most part, this is done by grazing. The animals grazing may be cows who are or will be raising calves, the calves themselves once they begin grazing or these same calves after weaning when forage is their primary source of nutrition.

In any of these scenarios the grass or legumes (possibly a combination of the two), in some stage of growth or harvest, is the main source of nutrients for these animals. Huge amounts of research have been conducted on managing forages to improve their “quality.” Quality refers to the nutritional value of the forage, regardless of the type or what stage it of growth or harvest it has been in. Methods to improve forage quality (nutritional value) include:

• Selections of the type of forages grown. Some plants naturally are more nutritious to the animal than others. For instance, Tifton 85 Bermuda grass is normally significantly higher in protein at the same stage of production compared to Bahia grass.

• Fertilization methods – types of fertilizer, when applied, how much applied, etc. Proper levels of fertilizers applied at appropriate times, give adequate moisture conditions can improve the quality and quantity of the forages grown.

• Timing of harvest – this may include rotational grazing, timing of cutting, baling, chopping or rolling for silage, etc. Normally, when forages are harvested at less mature stages of growth, the critical nutrient levels (protein, more soluble carbohydrates such as sugars, starches and cellulose are higher in volume as compared to less digestible fibers such as hemicellulose or lignin).

• Storage – we know that reducing the exposure of mechanically harvested forages to the elements can help retain a variety of nutrient values.

Consider the Soil Component

Often overlooked or minimized is the soil itself where these forage plants grow. Producers think about fertilizing or even the effects of grazing but the thought process often stops there. The soil is comprised of a variety of different components including minerals (~45%) some of which are actual nutrients for the plant, water (20 to 30%), air (20-30%) and organic matter (~5%). While the numbers shown are approximate and highly variable, roughly 15,000 to 20,000 different types of soils have been identified in the United States. While all the components of each of these are important, the organic matter component needs particular attention.

Let's consider some actual numbers. On average, an acre of soil 6 inches deep weighs approximately 2,000,000 pounds. If the organic matter component makes up five percent, that means the organic matter in the soil would weigh about 100,000 pounds (50 tons) per acre. This would equal around 2 semi-truck loads. Over time it takes at least 10 pounds of organic material to decompose to 1 pound of organic matter, so it takes at least 200,000 pounds (100 tons) of organic material applied or returned to the soil to add one percent stable organic matter under favorable conditions.

Soil organic matter (OM) is a variable and complex mixture of substances. It ranges from freshly deposited plant and animal materials to residual ‘humus,' which is a stable, organic compound (actually a group of compounds) that are relatively resistant to further rapid decomposition. In other words, humus is the final material present, once decomposition of plant and animal residue is fundamentally complete.

The elemental composition of OM includes carbon, oxygen, hydrogen, nitrogen, phosphorus, and sulfur. Nitrogen, phosphorus, and sulfur are plant nutrients that are slowly released during decomposition and are then available to plants, as well as other soil organisms. Other elemental nutrients such as various trace minerals like zinc (Zn), copper (Cu), manganese (Mn), iron (Fe) and selenium (Se) are also generally found in OM at varying levels. One very important component of OM is microorganisms (bacteria, fungi, protozoa, etc.) which are critical to the breakdown/decomposition of the plant and animal material. A healthy microbial population is critical to the continued recycling of plant and animal materials and the replenishment of the organic matter.

Like phyllosilicate clays (very fine clay particles formed from the breakdown of other minerals), OM has a cation exchange capacity (CEC). Cation exchange capacity is the ability for a clay or OM particle to attract or release cations which are positively-charged (+) particles. These particles are commonly minerals, and often nutrients important to the plant such as nitrogen (N), potassium (K) or phosphorus (P). By weight, OM has a much higher CEC than clays, and is, therefore, a very important source of this soil property, especially in wet soils and soils low in clay minerals (soils with higher levels of sand in their makeup.

This means that soils containing higher levels of OM generally are better at transporting important nutrients to the plant. On this note, interestingly, OM can also form complexes with metals and organic materials (including insecticides and herbicides), sometimes rendering them immobile and/or inert. This can prevent or at least reduce the possibility of these compounds “moving” to a water source or other area where potential toxicity could be a problem.

Yet another important physical property of OM is its ability to absorb and hold large quantities of water. The mass and volume of water that can be absorbed by OM often exceed the mass and volume of the OM itself. Thus soils with a higher OM are less affected by drought conditions than those with lower levels of organic matter.

As is evidenced here, an appropriate (generous) amount of organic matter is critical to the plant's ability to draw nutrients and water from the soil as play a variety of other important roles. Subsequently, it is in the beef producer's best interest, as he or she focuses on improving forage quality to manage pastures and hay meadow to retain and build OM levels.

This would be a good time to mention that the many areas of the country that have been so seriously affected by the droughts over the last few years may also have soils that experienced a reduction in OM contents. At the very least, these soils, may have been the victim of over grazing or other “survival” practices that interrupted the normal plant growth, dormancy and decomposition cycles that would normally have replenished normal OM levels. As such, special, specific management should be used in these areas to rebuild the damage done. Ignored, these soils may be significantly less productive compared to previous periods or to soils less affected by the adverse conditions.

Maintenance of Organic Matter Equilibrium

Soil organic matter consists of all materials found in, or on, soil that originate from organic material (plant and animal origin). It comprises both living and dead organisms and materials in various stages of decomposition and ranges in age from recent inputs to inputs thousands of years old. Of the OM, approximately 15 percent of this is ‘living' (made up of roots, fauna – insects and other animals – and micro-organisms such as bacteria, fungi, molds, etc.). The microbial component of this ‘living' pool changes rapidly and is considered essential for organic matter decomposition (especially microbial populations), nutrient cycling, degradation of chemicals and soil stabilization.

Organic matter decomposition regulates the flow of energy and nutrients in soil. It plays a key role in carbon (C), nitrogen (N), sulfur (S) and phosphorus (P) cycling and also acts to improve soil structure. Management and plant inputs influence both the quantity and quality of OM, which in turn directly impacts soil productivity and the ability of soil to recover from stress. The amount of organic matter in a soil is often used as an indicator of the potential sustainability of the growing system.

The optimal level of OM for any given soil is one which supports the functional capacity of the soil to hold and supply plant available water, store plant nutrients, provide energy for soil organisms and improve crop/biomass yields.

Effects on Water Introduction, Storage and Supply

Generally, forage production is limited by the capacity of soil to store and supply water to the plant. Soil texture and structure influence the amount of water that can be extracted from soil. This is influenced by the volume of water held in the soil and the depth to which root growth can access this water. Enhancing plant nutrition results in vigorous growth and increases the uptake of available water, thus increasing the efficiency of water use between the soil matrix and the plant.

An important effect of improved OM is modulation of water infiltration, permeability and storage. Poor soil structure (low OM) can lead to excessive soil and water loss from the soil surface, reducing water entry into the profile. Poor soil condition and loss of structure also results in surface sealing or compaction, reducing water entry and storage. Protection of the soil surface and retention of organic matter will help maintain soil structure.

Enhanced Soil Biological Function

A huge number and variety of organisms live in soil; some of which perform beneficial functions such as organic matter decomposition and nutrient cycling, while others are often associated with plant diseases. They all contribute to OM content. Some of these organisms are visible to the naked eye (earthworms, insects, etc.), but most are microscopic (bacteria, fungi, molds, etc.). Although not easily identified, the “biomass” of the soil micro flora is a useful measure of soil health and directly affects biological activity of the soil. Other factors affecting biological activity in soil include soil moisture, carbon availability, aeration, temperature, pH and plant type.

Here is a key point: This biological activity is one of the most important components of soil productivity and functions primarily within the OM portion of soils.

To optimize biological function our focus has to include:

• Development and maintenance of a diverse and resilient biological community. The total number of organisms, species diversity and activity varies with changes in the soil. Organisms carry out a wide range of processes that are important for soil health and fertility. They decompose and recycle organic matter, improve nutrient availability and soil structure, prevent disease, and degrade pollutants. A larger, more diverse microbial community decreases plant disease and ensures the recovery of essential soil functions after stress or disturbance.

• Support and enhance key functions of soil micro biota. Soil organisms recycle organic matter by feeding on dead plants and animals, manure, and other soil organisms. They break the OM into smaller particles for further decomposition by smaller organisms and play a key role in the transformation of plant available nutrients such as N, P and S. Nutrients in excess of microbial requirements are released in forms that are readily plant available and include nitrates, phosphates and sulfates. Stored nutrients may also be released when organisms die.

• Optimal biological functioning. Soil biology is vitally important in forage production due to the impact on plant health, as well as soil properties and processes. An active soil biota is essential to improve and sustain agricultural production. A healthy soil is a complex and dynamic system that is teeming with life, and includes all the organisms to ensure optimal soil function.

Conclusions

So why go into all this detail on soils and soil composition? The foundation of your cattle operation is your forage program. Cattle producers need to be as proficient in their management of forages as in their management of cattle. Exceptional management of forages STARTS with managing the soils and creating a nutritional environment where plant growth and productivity is optimized, just like we want nutrition and overall conditions optimized for the animals themselves. As previously stated, development of strong soils and a high quality forage program will dramatically reduce your production costs, improve animal productivity and improve operational profits.

Copyright 2014 – Dr. Stephen B. Blezinger. Dr. Steve Blezinger is a management and nutritional consultant with an office in Sulphur Springs, TX. He can be reached at sblez@verizon.net or at (903) 352-3475. For more information please visit us on at www.facebook at Reveille Livestock Concepts.







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