Ley Farming: Optimizing Grass & Legume Management

Ley farming is a system of farming whereby grasses and legumes are cultivated in a proper rotation for the production of hay and silage to meet the needs of livestock and enhance soil fertility.

Legumes

A legume is any plant from the Fabaceae family, including its leaves, stems, and pods. This family includes various legumes, such as beans, peas, lentils, soybeans, and peanuts.

Below are some examples of legumes:

a). Stylo (Stylosanthes gracilis):

A hairy perennial with small, pointed leaves that originated in South America and thrives in a wide range of conditions.

It grows well in less fertile soils, forms a dense mat, and mixes well with Jaragua and Rhodes grasses. It has a high nitrogen-fixing capacity and is established from seed.

However, at Serere Research Station in Uganda, it was found that it lowers the yield of cotton and sorghum planted after the resting phase, which is locally known as the "Stylo effect" and is under investigation.

As a farmer, you can join hands in investigating this in your own country.

b). Silver Leaf Desmodium (Desmodium uncinatum):

A somewhat hairy perennial legume that does well in wetter areas. Trailing stems readily root, and their hooked seeds cling to grazing animals and clothing, enabling them to spread. It is resistant to heavy grazing.

c). Green Leaf Desmodium (Desmodium intortum):

A robust perennial legume that grows best in areas with a lot of rainfall. This legume has hooked seeds and is resistant to heavy grazing, similar to Desmodium uncinatum in habit and production, but sets seeds more readily than Silver Leaf Desmodium.

d). Centro (Centrosema pubescens):

Centro is a climbing perennial legume with purplish flowers. It was introduced from South America and mixes well with tall, stemmy grasses. Centro requires soils of higher fertility than Stylo and is fairly drought-resistant, but it drops its leaves in long dry seasons.

It has higher protein content than Stylo and is most palatable.

e). Siratro (Macroptilium atropurpureum):

Siratro was bred by the Commonwealth Scientific and Industrial Research Organization in Queensland, Australia, from South American parents. It creeps on the ground and forms roots at the nodes.

The legume is easy to establish from seed, grows vigorously, and is highly palatable and nutritious. It gives nearly as much yield as Stylo. Siratro is both fire- and drought-resistant, and robustly survives heavy grazing.

f). Lucerne/alfalfa (Medicago sativa):

Lucerne, also known as alfalfa, is regarded as the most important fodder crop in the world. In Africa, it is mostly confined to the highlands of Kenya and around Lake Naivasha, where the altitude is high in Uganda.

It has small leaves with a stout taproot that can grow to a depth of more than three meters. Leaves tend to shed off during the dry season.

Production is best on deep red loam or deep alluvial soils. If fertilized well, lucerne can yield 5 to 7.5 metric tons of dry matter/ha in the first year and 2.5 to 5 metric tons/ha in subsequent years.

Under irrigation, it can give 8 tons/ha. Such high yields have been attained around Lake Naivasha. The legume is propagated by seed, and it is necessary to inoculate seeds with the right strain of Rhizobia bacteria before planting.

Seed rates range from 5 to 11 kg per hectare, depending on spacing. The spacing varies from half a meter to a meter inter-row.

g). Clovers (Trifolium species):

Clovers (Trifolium species) thrive at high altitudes, much like lucerne. White clover (Trifolium repens) can grow well in tropical grasses other than Chloria Guyana, but the latter inhibits white clover establishment from seed at a seed rate of 1-2 kg per hectare in a grass/legume mixture.

It can also be grown at fairly low altitudes. However, subterranean clover (Trifolium subterraneum), which is very useful in the United States of America, Australia, and South America, has not been successful in East Africa.

Herbage Conservation

Herbage, referring to leaves and grass consumed by livestock such as cows and sheep, is crucial to conserving to ensure a sufficient supply for winter feeding or year-round feed in stall-feeding systems.

Herbage conservation involves preserving an abundance of herbage during wet seasons to use when green grazing is not feasible, such as during periods of pasture shortage. This conserved herbage is fed to livestock in mid-latitude areas during winter and in hot and dry seasons in East Africa.

This practice prevents animals from losing condition and minimizes overgrazing that typically occurs during the dry season.

The preservation of herbage can be accomplished through hay or silage.

Pastures

Pasture refers to plants, like grass, cultivated to feed grazing animals. These pastures are classified into two types: permanent and temporary pastures, also known as leys.

Permanent pastures are areas of land that are planted with a mixture of grass and legumes and are not intended for arable cropping. The grass and legumes grow naturally, and their quality can be enhanced by practices such as topping, weeding, and rotational grazing.

Despite these efforts, the low nutritional value of permanent pastures limits their utility.

Ley Farming

In ley farming, arable crops are alternated with sown pastures, which are temporary in duration. Therefore, a ley is purposely sown as part of a rotational cycle to provide herbage for animals, comprising grass, legume, or a mixture of both.

The advantages of a ley include:

1. Restoring soil fertility as leguminous leys fix nitrogen from the air, releasing it into the soil. Organic matter from foliage and roots that decompose during the resting phase provides plant nutrients, enhances water absorption, and improves the soil's retentive ability.
2. Improving soil structure by building up organic matter.
3. Preventing soil erosion.
4. Breaking disease and pest cycles.
5. Bringing up plant nutrients from deeper soil layers to the surface.

Establishment of Leys

Leys can be established in two ways;

(i) Directly sowing pasture seed into bare soil involves plowing and leveling the land, then using a tractor-drawn planter (like the John Deere planter) or ox-drawn seeders (such as the Bental seeders) to drill the seed into the seedbed. Some farmers choose to broadcast the seed by hand and then use cattle to force the seeds into the soil by pulling branches of trees across the field, or by driving cattle around the field several times to drive the seeds into the soil.

(ii) Alternatively, a nurse crop can be used to establish leys. In this method, pasture seed is under-sown in a cereal or leguminous crop. The seed is broadcast into a standing crop like maize or sorghum before the last weeding and then hoed into the soil during weeding. The stalks of the nurse crop provide shelter to the young seedlings against wind and sunshine.

The following points should be noted:

Time of sowing: It is recommended to sow leys early in the rainy season. In areas with bimodal rainfall, sowing should be done during the main rainy season.

Seedbed: The ideal seedbed for leys is firm with a loose, fine tilth similar to that of finger millet.

Recommended grass and legume species: The recommended species of grass and legumes vary from country to country and from one ecological zone to another. Therefore, farmers should seek advice from competent officers in the Department of Agriculture or Veterinary Services before establishing pastures.

Seed inoculation: Seed inoculation involves mixing legume seeds with a special material containing nitrogen-fixing bacteria (Rhizobium species) before seeding. Inoculation of legume seed is the most effective way of providing legumes with the best strains of bacteria.

After germination, the bacteria enter legumes through root hairs and form root nodules. The size and shape of the root nodules and the strains of bacteria vary with each leguminous species.

This practice is particularly recommended for legumes that are not indigenous to East Africa, such as white clover and alfalfa. Inoculants can be obtained from the Kenya Farmers Association.

Fertilizers: Phosphorus is essential for the root development of both legumes and grasses. It should be applied in the seedbed as single superphosphate or double superphosphate.

Nitrogen encourages the vegetative growth of grasses, so nitrogenous fertilizers, such as sulfate of ammonia and calcium ammonium nitrate (C.A.N.), should be applied. Potassium should be applied as muriate of potash.

Weeding: Weeding should be done when necessary. Annual weeds invade leys first, but they disappear quickly and can be controlled by hand-hoeing, hand-pulling, or slashing. Perennial weeds are more serious, as they are unpalatable and of low nutritive value. Examples of perennial weeds include Sporobolus pyramidalis, Cymbopogon afro nardus, Digitaria scalarum, Solanum incanum, and Imperata cylindrical.

Grazing: Grazing should start 4-8 weeks after establishment when the sown pasture is about one-third of a meter high. If the first grazing is severe, pastures with shallow roots can be uprooted, and some of the damaged grass or legume species might not recover. Rotational grazing usually begins 3 to 5 months after establishment. It is important not to graze leys below 10 cm, as the ley species might be damaged.

A sound rotational grazing scheme must be followed because:

1. Roundworms and other internal parasites can be controlled by interrupting their life cycles.
2. By avoiding overgrazing, soil erosion is prevented, and there is always enough herbage available.
3. Pastures are given ample time to regenerate before being grazed again.
4. Cow dung and urine are evenly distributed throughout the farm, and rotational grazing ensures that the herbage is consumed when its nutritional quality is highest.
5. Since overgrazing is avoided, slower-growing grass and legume species that are highly palatable are not suppressed by faster-growing plants.
6. In Africa, it is recommended to graze pastures for one to two weeks and let them rest for the next four to eight weeks.

Fertilizer application in pasture management.

The use of small amounts of nitrate fertilizers leads to a rise in yield in certain African countries. The increase ranges from less than 13-20 tons of dry matter per hectare with the application of 40kg/hectare in the first year, and 80kg/hectare in the following years.

Nonetheless, the typical suggestion is to apply 100-200 kg/ hectare per year.

Conservation

We use 7-15 kgs of molasses per ton of grass here. When soaked in a molasses solution, the pH drops to less than 4. Elephant grass in silage has moderate dry matter losses and does not settle easily.

Herbage Yields

On good, heavily fertilized soil, and in a warm, humid climate or under irrigation, elephant grass is capable of producing high yields of herbage.

According to records, one of the export locations achieved the highest recorded yield of 310 tons of fresh material or 71.9 tons of dry matter per hectare per year.

In dry conditions, 87 tons of fresh material, or about 87 tons of dry matter per hectare per year, have been recorded.

Elephant grass can grow in association with legumes, such as green leaf Desmodium (Desmodium intortum), silver leaf Desmodium (Desmodium uncinatum), and centro (Centrosema pubescens), without any problems.

Use of fertilizers

Fertilizers are utilized to enable crops to produce enough food to sustain both the livestock and human population. These fertilizers provide crops with essential nutrients like potassium, phosphorus, and nitrogen, which facilitate growth, increase yield, and improve food production.

Commercial fertilizers emerged due to a deficiency or imbalance in the nutrient supply. Plants derive their nutrients from the air, water, and soil.

Oxygen and carbon dioxide come from the air, while carbon dioxide and hydrogen come from the water. All other nutrients are obtained from the soil. Sixteen elements are necessary for normal plant growth, including nitrogen, phosphorus, potassium, carbon, hydrogen, oxygen, calcium, sulfur, nickel, cobalt, murinite, iron, copper, zinc, and chlorine.

The lack of these nutrients can lead to inadequate growth or plant death. Some of these elements are required in large quantities, including carbon, hydrogen, oxygen, nitrogen, phosphorus, potassium, magnesium, and sulfur, while the rest are micronutrient elements.

Elements of Fertilizers

Nitrogen, phosphorus, and potassium are the three main primary nutrients found in commercial fertilizers, and each nutrient has a vital role to play in plant nutrition. Nitrogen is considered to be the most crucial nutrient, and plants absorb more nitrogen than any other element.

The soil contains a minimum of 13 essential nutrient elements, and Calcium and Magnesium are frequently added as lime and are hence referred to as lime elements.

Argon is found in numerous commercial fertilizers, while Nitrate, Phosphorus, and Potassium are regularly applied as fertilizers, making them known as fertilizer elements.

1. Nitrogen

The effects of Nitrogen on plant growth have been extensively studied, and it is known to have the greatest impact among all fertilizer elements. This is because most soils are deficient in Nitrate as a result of excessive loss through drainage, volatilization, or as Carbon in an unavailable form.

However, certain plants, such as legumes, can fix free Nitrogen into usable forms through symbiosis.

Apart from this, Nitrogen is a crucial component of the chlorophyll molecule, which is responsible for capturing sunlight energy during photosynthesis and driving plant growth and grain yield.

Within the plant, Nitrogen plays a vital role in ensuring that energy is available at the right time and place for optimal yield.

Positive Effects of Nitrogen on Plant Growth and Development.

It enables the plant to capture solar energy through photosynthesis, which fuels plant growth and increases grain yield.

It promotes negative growth above the ground and enhances the deep green color of leaves. In cereals, it improves grain plumpness and increases protein percentage.

In all other crops, Nitrogen is a primary factor that governs the utilization and application of Phosphorus, potassium, and other nutrients.

Plants with insufficient Nitrogen exhibit skewed growth and a limited fruit system. The leaves turn yellowish-green and ultimately fall off.

Effects of Over-Application of Nitrogen

The application of Nitrogen often leads to undesirable consequences, including the degradation of soil, water, and air quality. Farmers tend to over-apply Nitrogen due to its general effects on plants, but this is unfortunate as Nitrogen fertilizer is costly and easily lost in the soil.

Excess Nitrogen results in dark and soft green leaves, delays crop maturation, and weak stems, affects the quality of fruits or greens, and reduces the disease resistance of crops.

Nevertheless, the application of Nitrogen on pasture often produces good yields.

Forms of Soil Nitrogen

Soil nitrogen is present in three main forms: organic nitrogen compounds, ammonium (NH₄⁺) ions, and nitrate (NO₃⁻) ions.

The majority of nitrogen in the soil exists in organic form, as it is linked to microbial activities. The fixed form is mostly found in the subsoil, whereas the ammonium and nitrate forms are present in small amounts due to continuous loss through drainage and volatilization.

A variety of common fertilizers are available on the market, including Sodium Nitrate, Ammonium Sulphate, Urea, Calcium Cyanide, Ammonia Liquor, Anlychous Ammonia, and Amino Phosphate.

2. Sulphur

Sulfur is essential for a variety of growth functions in plants, such as nitrogen metabolism, enzyme activity, and protein and oil synthesis. In general, plants that are deficient in sulfur have short and/or spindly stems and yellowing of the young (top) leaves. When nitrogen deficiency occurs, the yellowing first affects the older, lower leaves.

Sulfur is crucial for various living organisms, as it is a constituent of amino acids such as methionine and cystine in humans, plants, and other animals.

Its deficiency can result in severe malnutrition in animals. Furthermore, sulfur is a component of vitamins like biotin and thiamine, and most protein structures contain sulfur groups.

Sulfur also plays a role in the properties of some enzymes, and plants that lack sulfur tend to be small and spindly.

Sulfur is typically found in many fertilizers and is applied as such. Legumes, clover, and soya beans, among others, require high amounts of sulfur, while grasses and most cereals generally have a low sulfur requirement.

3. Phosphorus

Except for Nitrogen, no other plant nutrient is as critical as Phosphorus, in that most Ugandan soils have a deficiency of phosphorus. Lack of Phosphorus has a double effect, i.e., on root development and green coloration. Phosphorus promotes early root growth, winter hardiness, and seed formation, stimulates tillering, and increases water use efficiency.

It affects legumes more profoundly, and the contribution of Phosphorus to plant growth can be seen in the following processes;

1. Cell division and fat formation.
2. Flowering, fruiting, and seed formation.
3. Crop maturation, in this way it counteracts the effects of excess Nitrogen.
4. Root development, especially lateral and fibrous rootlets.
5. It also contributes to the strengthening of the straw in crops and therefore prevents bending.
6. Affects crop quality, especially forages and vegetables.
7. It also encourages resistance to certain diseases.
8. In most soils, Phosphorus is tied up in soluble forms and only a small amount is available to plants. The removal of Phosphorus from the soil by crops is lower compared to Nitrogen and potassium, and higher fertilizer rates of Phosphorus show that most of it is turned into unavailable forms once it reaches the soil. Phosphorus is commonly lost by crop removal, leaching, erosion, and fixation into soluble forms.

A list of fertilizers with phosphorus includes superphosphate (single and double), Ammonium phosphates, Ammonia led, Superphosphate, Phosphoric acid, Steamed bone meal, and Super phosphoric acid.

4. Potassium

Potassium's role in plant tissue is linked to the movement of water, nutrients, and carbohydrates. It activates enzymes within the plant, affecting protein, starch, and ATP production, which, in turn, regulates photosynthesis.

The presence of Potassium in the soil is related to the vigor and appearance of plant growth. Potassium is also responsible for increasing resistance to some diseases, preventing bending, and counteracting the effects of excess Nitrogen.

Additionally, Potassium balances the effects of both Nitrogen and Phosphorus, playing a part in the starch formation, translocation of sugars, development of chlorophyll, and cereal or tuber formation.

It is believed that plants can hold more Potassium than necessary and release it back into the soil. Plants lacking Potassium have dry, irregular leaves with scorched edges and experience issues with photosynthesis and starch formation.

Fertilizer forms of Potassium include Potassium Chloride, Potassium Sulphate, Manure salts, and Potassium Nitrate, among others.

Conclusion

In conclusion, ley farming is a beneficial system that combines the cultivation of grasses and legumes in rotation to provide hay and silage for livestock while enhancing soil fertility. Legumes, such as stylo, desmodium, centro, siratro, lucerne, and clovers, play a crucial role in ley farming by fixing nitrogen, improving soil structure, preventing erosion, and bringing up nutrients from deeper soil layers. Establishing leys can be done by directly sowing pasture seeds or using a nurse crop. Proper sowing time, seedbed preparation, seed inoculation, fertilization, weeding, and grazing management are key factors for successful ley establishment and maintenance.

Conserving herbage through hay or silage is essential to ensure a sufficient supply of feed during periods of pasture shortage or when green grazing is not feasible. Rotational grazing schemes help control internal parasites, prevent overgrazing and soil erosion, evenly distribute cow dung and urine, and allow pastures to regenerate before being grazed again.

Fertilizer application, particularly nitrogen, phosphorus, and potassium, is vital to sustain crop and livestock production. Nitrogen, in particular, plays a crucial role in plant growth and yield by fueling photosynthesis and providing energy to the plant. Understanding the role of these essential nutrients and their application is important for optimizing crop and forage production.

By adopting ley farming practices, conserving herbage, and implementing proper pasture and fertilizer management, farmers can enhance livestock feed production, improve soil fertility, and promote sustainable agricultural systems.