Chapter 3: Plant perennial crops

Perennial crops are essential components of sustainable agricultural systems in Kenya, providing long-term yields and contributing to food security and income generation for smallholder farmers and commercial enterprises alike. Their production requires specialized knowledge and management practices adapted to the unique growth cycles and environmental requirements of these crops. This chapter focuses on the practical aspects of planting perennial crops, emphasizing the selection and use of appropriate farm inputs to optimize growth and productivity in diverse Kenyan agro-ecological zones.

3.1 Plant perennial crops

Planting a perennial crop takes careful planning, a suitable species and variety, and good-quality inputs, because the crop will occupy the field for many years. Tea, coffee, macadamia, avocado and mango are important perennial crops for Kenyan livelihoods and the economy. Extension officers must understand the farm inputs a planting needs and how to use them correctly, so that the crop establishes well and stays productive.

3.1.1 Types of farm inputs

Farm inputs are the resources used in crop production to improve growth, yield and quality. For a perennial crop, the inputs must support the establishment phase and also long-term management over several years. The four types below are the ones a farmer needs at planting: inorganic fertilisers, seeds, vegetative propagation materials and manures. The choice and management of each one affects the cost of establishing the crop and its later yields.

3.1.1.1 Inorganic fertilizers

Inorganic fertilisers are manufactured products that supply plant nutrients in a concentrated form. At planting they supply the nutrients a young plant needs to build roots and shoots before it can draw enough from the soil. Straight fertilisers supply one main nutrient, for example urea or calcium ammonium nitrate for nitrogen, triple superphosphate for phosphorus and muriate of potash for potassium. Compound fertilisers such as NPK mixtures and DAP supply more than one nutrient in each granule.

• Nitrogen (N): Promotes leaf and shoot growth and gives the plant a good green colour, but too much at planting can scorch young roots.
• Phosphorus (P): Encourages strong root development, so a phosphorus fertiliser is usually the main one placed in the planting hole.
• Potassium (K): Helps fruit development, quality and the plant's resistance to stress and disease.
• Micronutrients: Zinc, boron and copper are needed in small amounts for enzyme functions and crop health. A deficiency in a mango or avocado orchard may be corrected with a foliar spray.
• Lime and pH adjusters: Acidic soils, which are common in highland areas, may need lime to raise the pH and improve nutrient availability for crops such as coffee, avocado and macadamia. Tea grows best in acid soil and is not limed.
• Soil testing: The type and amount of fertiliser are based on a soil test and on the recommendation for the crop, not on guesswork.

Fertiliser is mixed with the soil at the bottom of the planting hole, never placed in direct contact with the roots. As an illustration, if the recommendation for a crop is 200 g of DAP in each hole and a farmer is planting 500 holes, the total is 200 g × 500 = 100 000 g = 100 kg, which is two 50 kg bags. Fertiliser is stored dry, on a pallet and away from seed and chemicals.

3.1.1.2 Seeds

Seeds are used as direct planting material for some perennial crops and, more often, to raise seedlings and rootstocks in a nursery. The seed bought must be of the right variety, viable, free from disease and from a reliable source. Seed from a certified supplier carries the variety name, batch and expiry date on the pack, and the Kenya Plant Health Inspectorate Service (KEPHIS) regulates seed quality.

• Genetic quality: Improved varieties developed by research institutions such as KALRO give better yield, disease resistance and adaptation than unselected seed.
• Viability: Fresh seed germinates better, and some tree seeds lose viability quickly, so they are sown soon after extraction.
• Purity and health: Seed free of other seeds and disease prevents early crop losses. In coffee, clean nursery practice helps to reduce the spread of diseases such as coffee wilt.
• Pre-treatment: Some seeds need soaking or scarification to break dormancy and improve germination.
• Quantity: The farmer calculates the amount of seed from the number of plants required and allows for some that will fail.

3.1.1.3 Vegetative propagation materials

Vegetative propagation materials are the parts of a plant used to start a new one, such as suckers, splits, slips, crowns and cuttings, and also grafted and tissue-cultured plants raised by nurseries. They reproduce the parent exactly, which gives uniform crops that often mature early. The material must come from healthy, true-to-type mother plants, because it carries any disease the parent has.

• Health status: Disease-free material prevents early losses. Tissue-cultured banana plantlets, for example, start free of many diseases and are more uniform than ordinary suckers.
• Source reliability: Certified nurseries inspected by KEPHIS supply material that meets quality standards.
• Appropriate age and size: Material should be at the right stage for planting, neither too young to survive nor so old that it is stunted, so that shock is reduced and establishment is quick.
• Root system: A healthy, undamaged root system takes up water and nutrients better. Avocado seedlings with well-developed roots establish faster and resist dry spells better.
• Handling and transport: Material is kept shaded and moist, protected from wind and sun during transport, and planted as soon as possible after delivery.

3.1.1.4 Manures

Manures are organic materials from animals or plants that improve soil structure and supply nutrients slowly as they decompose. They include farmyard manure, poultry manure, compost and green manure. At planting, manure is mixed with the topsoil that goes back into the planting hole, so that roots meet a loose, moist, fertile soil. A farmer who keeps dairy cattle, for example, can use the manure to plant coffee or avocado without buying much fertiliser.

• Farmyard manure: From cattle, goats or sheep, it improves soil structure and moisture retention and supplies nutrients over time.
• Poultry manure: It is richer in nutrients than cattle manure, so it is used in smaller amounts and must be well decomposed.
• Compost: Made from decomposed crop residues, weeds and kitchen waste, it improves soil structure and microbial activity.
• Green manure: Legume or other plants grown and incorporated into the soil to add organic matter and nitrogen before the perennial crop is planted.
• Quality and safety: Manure must be well decomposed before use, since fresh manure can burn roots, introduce weed seeds and carry pests.

The amount of manure per planting hole depends on the crop and the size of the hole, and is measured, for example by the bucket, according to the extension recommendation.

Other farm inputs

Water for irrigation and the products used to control pests and diseases are also farm inputs. They are not needed in the planting hole in the same way as fertilisers, seeds, planting materials and manures, so their selection and use are taught under the management of established perennial crops.

Chapter Summary

This chapter covered the essential aspects of planting perennial crops, starting with the various types of farm inputs required for successful cultivation. These inputs include inorganic fertilizers, seeds, vegetative propagation materials, and manures, each playing a crucial role in crop growth and soil fertility. Different planting methods were explored in detail, such as direct seeding, transplanting, drilling, broadcasting, and row planting, highlighting their specific applications and suitability for perennial crops. The chapter also examined the advantages and disadvantages associated with each planting method, providing insight into their practical implications for farm management. Emphasis was placed on the importance of maintaining accurate annual crop planting records to facilitate effective monitoring and decision-making. Finally, the procedures for establishing perennial crops were outlined, ensuring a comprehensive understanding of the steps involved in successful crop establishment. This holistic approach equips learners with the knowledge to manage perennial crop production efficiently.