Seed Treatment Tips for Healthy Pasture Management

Seed Treatment

Seed treatment is a process in which seeds are treated to increase either their germination percentage or resistance to soil organisms such as fungi and insects. This involves the application of biological, physical, and chemical agents to the seeds to provide protection and improve the health of crops.

To increase resistance against soil organisms, seeds may be treated with fungicides or insecticides that are commonly available in farm stores. Some seeds have tough coats that need to be altered in texture to either enhance or remove the coat, thereby increasing their germination rate.

Legumes usually have impermeable hard coats that prevent water from penetrating, resulting in a low germination rate. By altering the texture of such seeds, the germination rate will increase and the seed rate will be reduced, leading to a higher rate of establishment.

Several methods of altering seed texture have been used;

1. Immersing in reagents like concentrated sulphuric acid (90%), potassium nitrate, thiourea, or ethylene.
2. Dip in freezing water at 17°c or pre-chilling (soaking seeds in cold water for some time before planting).
3. Use of liquid nitrogen at 196°c.
4. Dipping in boiling water.
5. Mechanical scarification (greatly applicable in the field).

Seed treatment for proper livestock pasture management.

Seeds are subjected to mechanical scarification by rubbing them between two sheets of sandpaper coated with silicon carbide. Another method of scarification is by piercing the pericarp with a sterile pin. Seed treatment can enhance the health of crops by boosting their immunity and ensuring uniform germination.

Types of Seed Treatment

1. Seed coating.
2. Seed pelleting.
3. Fungicidal and insecticidal dressing.
4. Seed hardening.
5. Fortification.
6. Infusion.
7. Osmotic priming.
8. Fluid drilling and separation of viable seeds.

Seed Selection Depends upon the Following Factors

1. Select whole seeds. Broken or crushed seeds should be avoided.
2. The sowing quality of seeds should be high.
3. They should have a high germinating capacity.
4. Seeds should be free from infection.
5. The seeds should not be mixed with seeds of weeds or with other seeds.

Seeds can be tested in the following ways

1. Cover Crop Testing.
2. Germination and Vigor Testing.
3. Purity Testing.
4. Seed Health Testing Methods.
5. Trait Testing.

Examples of Seeds That Undergo Seed Dormancy in Pasture Establishment

1. Stylo (Stylosanthes gracilis): Treatment is done by deep freezing at 17°C for 7 days or immersion in boiling water for 10 seconds. Such treatments increase the germination percentage from 20% to 80%.
2. Centro (Centrosema pubescens): The response is based on one second in boiling water or 16 days of deep freezing. This revises the germination percentage from 30% to Siratro. When dipped in concentrated sulfuric acid for 15 minutes, it raises the germination percentage from 18% to 94%. Hot water treatment seems to be one of the easiest and most successful methods.

Sowing Depth

The optimum sowing depth for different plant species varies according to the soil type, rainfall, and soil conditions at sowing. However, as a general rule, the seeding depth should be about five times the size of the seed. Shallow sowing is crucial for better germination, as most grass and legume seeds are small.

The sowing depth should be four or five times the diameter of the seed. For some pasture seeds, row spacing may be necessary, especially when a tractor is used for inter-row weeding.

This is particularly important in grass pasture species such as elephant or Napier grass (Pennisetum purpureum).

Elephant grass (pasture species).

Seed Quality Parameters

1. Seeds should be genetically pure.
2. Should contain optimum moisture content.
3. It should be free from a mixture of other seeds.
4. Should be healthy and free from infection or infestation.
5. The seeds must not have any damage to any of their parts.

Choice of Pasture Species

Pure and mixed stands

The pure stand refers to the cultivation of a single grass pasture, while the mixed stand involves the growth or planting of a mixture of grass and legume pasture in the establishment of leys. In the tradition of establishing leys, it is common to sow mixtures of grasses and legumes.

Advantages of mixed stands

1. Mixed stands ensure persistence, that is to say, there is rapid establishment of grass/legume grass mixtures.
2. Mixtures ensure variety in palatability and increased production.
3. They also maintain soil fertility, especially the grass/legume mixtures.
4. They also control soil erosion due to different growth forms.
5. There is proper utilization of nutrients, as different plant species tend to have different nutritional requirements.
6. It also makes it easy to weed control since most of the space is covered by the pasture.
7. There is also increased herbage/ fodder production. 

Selection of Pasture Species

When selecting species for planting, we consider the following factors: high-yielding species, high germination percentage, type of soil, the climate of the area, palatability of the pasture, grazing system to be applied on the farm, type of animal to be kept on the farm, growth rate of the plant species, duration of the ley, and finally, the leafiness, or leaf-stem ratio, of the species.

For long-term pastures (permanent pastures), the following factors should be kept in mind.

Nitrogen accumulators are mainly legumes. Rapid soil cover is provided by, for example, creeping grass, which is either stoloniferous or rhizomatous. Some short-duration perennials are also effective soil cover species.

Certain permanent species, such as star grass, which takes five years or more to establish, are also good nitrogen accumulators.

Lastly, closely matting species, referred to as bottom-filling species, also contribute to soil nitrogen levels. Early and late maturing species of grasses and legumes in terms of production and value.

When choosing a pasture grass or legume, the main objectives are to prioritize productivity, palatability, nutritive value, and adaptation to the environment.

Note:

1. Productivity refers to the local yield of the crops and their influence on the multiplicity of the crop.
2. Palatability is the readiness with which the herbage of a particular species is eaten by livestock.
3. Nutritive value refers to the portion of the plant that will be used by the animal for maintenance and production.

Factors Affecting Productivity and Yield of Pastures

1. The ability to survive and spread vegetatively, that is to say, its persistence when planted.
2. Ability to survive the competition of other associated species, that’s to say, its aggressiveness when planted in an area.
3. Ability to recover from hard grazing and trampling by animals.
4. Drought resistance or tolerance to cold weather.
5. Seasonal distribution of production.
6. Ability to produce a good yield of viable seeds or the ability to establish cheaply by vegetative means.
7. Soil fertility incurrence especially the maintenance of high nitrogen levels.
8. The climate of the area where the pasture is to be established.

 Factors affecting the palatability of pastures

We should consider the type of plant species, the stage of growth of the plant, soil quality, pasture quality, the nutritive value of the pasture, seasonal changes in the area, grazing heights of the animals, the leaf-to-stem ratio of the pasture, grazing pressure by animals, the management of herbage, and the use of alternative feeds.

Additions to herbage, such as urea, must also be considered.

Weed Management in the Seeded Pasture

A weed is a plant growing where it is not desired by man, i.e., a plant that is out of place. Weeds hurt crop yield by competing for resources such as water, nutrients, and light. They also reduce crop quality by interfering with harvesting, and some of them are poisonous to livestock.

Here are some of the common pasture weeds:

Goat weed (Ageratum conyzoides): This annual herb grows up to one meter tall and has pale blue flowers. It is common in southern Uganda and the Nyanza district of Kenya and can be controlled using growth-regulating herbicides such as 2,4-D and paraquat, a contact herbicide.

Macdonald weed (Galinsoga parviflora): Originally from South America, this annual weed is now widespread in Africa. It has white flowers and belongs to the Compositae family. It produces many seeds that germinate readily and can be controlled using paraquat, simazine, and 2,4-D.

Witch weed (Striga species): Striga is an annual parasitic herb with brightly colored flowers, including purple witchweed (Striga hermontheca) and red witchweed (Striga asiatica), which are common in Tabora, Tanzania, and Bukedi and Teso in Uganda.

The weed attaches its roots to the roots of crops such as maize, finger millet, and sorghum to obtain nutrition. Striga can be controlled by using trap crops or by applying herbicides such as MCPA and 2,4-D.

Blackjack (Bidens pilosa): This annual cosmopolitan herb grows up to over half a meter and belongs to the Compositae family. Its stem is four-angled, and its fruit is black with hooks. Blackjack seeds can remain dormant for up to eight weeks, and the weed can be controlled by using MCPA, 2,4-D pre-emergence or post-emergence, or contact herbicides such as paraquat.

Tick-berry (Lantana camara): This perennial shrub belongs to the Verbenaceae family and has pinkish-purple flower heads with yellow centers and blackberries. It is commonly found in wastelands or abandoned cultivated areas and can be controlled by cutting down thickets or applying 2,4-D. Biological control using insects has not been successful.

Oxalis (Oxalis latifolia): This perennial weed is bulbous and belongs to the Oxalidaceae family. It has rhizomes that develop with the bulbs, and the inflorescence is an umbel with 5 to 15 flowers. Oxalis is common in coffee and banana-growing areas of Uganda and the highlands of Kenya and is difficult to control because of the many bulbils produced by the rhizomes.

Chemical control, such as using amitro and glyphosate, is the most promising method, while cultural means are ineffective.

Thorn apple (Datura stramonium): This weed of arable crops and wasteland belongs to the Solanaceae family and is an annual herb with white funnel-shaped flowers and thorny fruits containing many dark brown seeds. The leaves are poisonous to cattle, and the weed can be controlled using simazine, dinoseb, and 2,4-D.

The Wandering Jew (Commelina species): It is a perennial herb with fleshy leaves and roots at the nodes. It belongs to the family Commelinaceae, and there are two commonly found species in Africa, namely Commelina benghalensis with blue flowers and Commelina Africana with yellow flowers.

The plant is resistant to most herbicides; however, seedlings are susceptible to auxin-type and paraquat herbicides.

Mexican marigold (Tagetes minuta): It is an annual herb from the Compositae family with yellowish flowers and strongly scented leaves. It produces a large number of black seeds and is one of the most widespread weeds in East Africa, particularly in wastelands and burned areas.

Young Mexican marigold plants can be controlled using growth-regulator (auxin) herbicides like 2, 4-D, and 2,4-DB.

Couch grass (Digitaria scalarum): Also known as lumbugu in Uganda, Sangare in Kenya, and Thangari in Tanzania, is a perennial grass with underground rhizomes. It is the most significant rhizomatous weed in East Africa and is commonly found in areas of high rainfall where coffee, bananas, tea, and pyrethrum are grown.

Couch grass is difficult to control through cultivation, but can be effectively controlled using herbicides like dalapon, aminotriazole, and glyphosate.

Wild finger millet (Eleusine species): It is an annual grass commonly found on arable land and near cattle tracks. There are two species found in Africa, Eleusine Africana and Eleusine indica, and their inflorescence consists of 5 to 8 spikes that form an umbel. The weed can be controlled using hand hoeing and pre-emergence herbicides like atrazine and linuron.

Sword-grass (Imperata cylindrical): Also known as lalang grass, is a perennial grass with a deep and extensive system of rhizomes. Its leaves are stiff and upright with tapering tips, and the inflorescence consists of a fluffy, cylindrical spike-like head.

The weed is a problem in coffee in southern Tanzania, coconut and sisal plantations in coastal Kenya, and cotton in eastern Uganda, and can be controlled using dalapon and sodium arsenite.

Bristly foxtail (Setaria verticillata): Also called love grass, is a tufted annual with a bristly, cylindrical inflorescence made up of numerous spikelets. It sticks to clothing and the coats of animals and is a common weed in coffee in Kenya and wheat and barley growing areas in Kenya, and the Sebei district in Uganda.

It can be controlled through mowing or pre-emergence herbicides like prometryne, 2,4-D, and atrazine.

Star grass (Cynodon dactylon): Also known as Bermuda grass, is a rhizomatous perennial weed found in old kraal areas. It is difficult to control through cultivation, but it is susceptible to the herbicide dalapon. The inflorescence consists of purplish spikes in a star-like arrangement

Advantages of Weeds

Weeds play a vital role in controlling soil erosion by providing adequate surface coverage, for example, Oxalis Latifolia and Oxalis Corniculata.

Some weeds, like Amaranthus species, are edible and can be used as food for humans. Additionally, weeds can also be used as medicine, such as Oxalis corniculata.

Weeds enrich the soil by adding organic matter and mineral nutrients when they decompose. They are also valuable genetic material and can be used as sources for crop breeding.

Some weeds are aesthetically pleasing and used for ornamental purposes, and they provide a habitat for beneficial insects. Furthermore, weeds provide nectar for honey making.

Weeds are also a crucial food source for wild animals, particularly in areas where national parks are significant sources of foreign exchange.

Disadvantages of Weeds

Weeds compete with crops for various resources, including plant nutrients, soil moisture, soil air, light, and space.

Some weeds are toxic to humans and livestock, such as the leaves of Thorn Apple (Datura Stramonium) and the green berries of Tick Berry (Lantana Camara).

Aquatic weeds, such as Nile Cabbage (Pistia Stratiotes) and Water Hyacinth (Eichhornia Crassipes), can cause clogging in waterways, rivers, and lakes, making navigation difficult. For instance, the Water Hyacinth in the Nile River in Sudan is so abundant that it encroaches on fishing grounds.

Weeds negatively impact the formation and distribution of crop roots. In plots heavily infested with weeds, there are fewer roots per crop.

Weeds also reduce crop yields by reducing the size and height of the plant, thereby reducing the photosynthetic area and the amount of carbohydrates produced by photosynthesis.

Weeds also lower the quality of crops, for example, Black Jack in cotton gardens, which sticks to the lint and reduces cotton yields.

Wild Onion can also affect the quality of milk produced by lactating cows by giving it a bad odor and color.

Some weeds are hosts for destructive pests of commercial crops, such as the Cotton Strainers (Dysdercus species) and Cotton Lygus (Tayloriygus Vosseleri) in the cotton industry.

Weeds also decrease the market value of crops and lead to extra work during cultivation and harvesting.

Additionally, some weeds are parasitic on crops, such as Witchweed (Striga Asiatica and Striga hermonthica) on sorghum roots and Mistletoe (Phoradenron species) on fig trees and avocado pears. The parasites obtain part of their sustenance from the host and produce some carbohydrates from the air.

Effects of Pasture Weeds on Livestock

The effects of pasture weeds on livestock can be significant. Some pasture weeds, such as Lantana Camara, Phytolacca dodecandra, and most of the Solanaceae family, are poisonous.

These plants can affect the health of animals if they ingest them, depending on the level of toxicity, availability of alternative vegetation, and the animal's adaptability.

Some weeds also have negative impacts on grazing convenience, such as thorns or less palatability.

Other weeds can affect the quality of milk or meat by adding unwanted flavors or by having low nutritional value.

The presence of weeds can also increase the cost of agriculture and hinder the progress of work by increasing irrigation requirements, reducing the value of produce, or adding cleaning costs.

Some weeds, such as Cleome viscosa, can also produce an undesirable odor in milk if eaten by dairy animals.

Control of Weeds for Good Pasture Management

Control of weeds can be achieved through various methods such as pulling, digging, disking, plowing, and mowing. The success of these methods depends on the life cycle of the target weed species.

Preventative measures include sanitation of non-crop areas on farms, quarantine of animals that may carry weeds, use of clean seeds, and screening of irrigation water.

Physical control methods include mechanical tillage, mowing, hand pulling, hoeing, and cutting, as well as burning.

Cultural control includes selecting more competitive crops, crop rotation, and proper fertilizer placement.

Conclusion

In conclusion, seed treatment is an essential process in agriculture that enhances the germination rate and improves the health of crops. Through the application of biological, physical, and chemical agents, seeds can be protected against soil organisms, and their coats can be altered to increase permeability. This results in higher establishment rates and improved crop productivity.

Proper seed selection is crucial for successful pasture establishment. High-quality seeds that are genetically pure, have high germination capacity, and are free from infection or mixture with other seeds should be chosen. Seed quality parameters such as moisture content and damage should also be considered. Additionally, the choice of pasture species and the establishment of pure or mixed stands play a vital role in ensuring the persistence, productivity, and palatability of pastures.

Weed management is another important aspect of pasture establishment. Weeds can hurt crop yield and quality by competing for resources and interfering with harvesting. Understanding common pasture weeds and implementing effective control measures, such as herbicides, can help minimize their impact. However, it's important to note that some weeds also have advantages, such as soil erosion control, providing habitat for beneficial insects, and being a food source for wild animals.

In summary, seed treatment, proper seed selection, choice of pasture species, and effective weed management are all key factors that contribute to successful pasture establishment and long-term productivity. By implementing these practices, farmers can ensure healthier and more productive pastures for their livestock.