Eggplant Integrated Pest Management AN ECOLOGICAL GUIDE

___________________________________________________________________________________Major Agronomic PracticesWhen selecting mulch material, it is important to consider your requirements and the characteristics ofthe material. For soil protection the use of high C/N ratio (high carbon content: usually “dry” materials)material are recommended. Examples of high C/N ratio materials are straw, lemon grasses and coconutleaves. These last for a long time. For soil fertilization purposes, low C/N ratio material (high nitrogencontent: usually “wet” materials) are recommended. Examples are leguminous grasses, leguminouscrops, and compost.Leguminous crops, such as clovers, can also be grown as a “living mulch”, together with the main crop.Such living mulch is an effective soil protectant and it provides nitrogen to the main crop. See section3.8.3.2 above.Nematode control with manure?Fresh manure may have an effect on the occurrence of diseases such as rootknot nematodes:some studies report that adding fresh organic matter such as poultry manure, cattle manure anddifferent kinds of green manure greatly reduced infestations of rootknot nematodes. See section8.1.3 on rootknot nematodes.Reasons for this control are not clearly understood but may be caused by the ammonia gas (NH 3)that is produced during decomposition of the manure, and the manure may also give plants agrowth “boost” allowing extra root growth for compensation of nematode-damaged roots.In areas where rootknot nematodes are a problem, testing the effects of fresh manure may be aninteresting management option.3.8.4 Chemical fertilizersInorganic or chemical fertilizers are usually added for the short term food needs of the plants.The three main elements in chemical fertilizers are nitrogen (N), phosphate (P) and potassium (K).Chemical fertilizers can usually be bought separately or in a combination with different proportions. Acombination of the three fertilizers is described by a series of three numbers referring to the content ofeach element. For example: 25-15-5 means the fertilizer contains 25% N, 15% P and 5% K.Some micronutrients such as boron can be bought separately, however, additions of micronutrientsshould be made only when a deficiency is indicated, preferably by a soil test analysis.3.8.5 Comparing organic and chemical fertilizersThe following table lists advantages and disadvantages of organic and inorganic (chemical) fertilizers.AdvantagesDisadvantagesOrganic fertilizerRich in nutrients.Usually provides both (part of the)macronutrients N, P & K, and a range ofmicronutrients.Improves soil structure.Increases water holding capacity of thesoil.Gradual release of nutrients over a longperiod of time.Improves nutrient exchange system.Stimulates activity of micro-organisms thatmake nutrients from the soil available toplants.Organic fertilizers such as compost varywidely in composition, depending on theraw material used in their preparation.Inorganic fertilizerHigh content of a few nutrients.Fast release of nutrients.Easy to determine dosage.Easy to apply, not labor intensive.Usually very water soluble; may bewashed away quickly during wetseason.Expensive.30Eggplant Ecological Guide