Studies on green manure application and intercropping in coffea arabica l. production

Abstract

Three experiments were conducted between May 1991 and December 1993 at Coffee Research Station Ruiru. Kenya, to study the effect of green manure application and intercropping on soil chemical properties, coffee plant growth, bean yield and quality. The first experiment was to study the effect of applying as mulch various leguminous green manures plants to coffee (Goftea arabica Cv. 'Ruiru 11') at field establishment phase. The leguminous green manures tested were from Leucaena leucocephala, Sesbania sesban, Galliandra calothyrus, Medicago sativa, Desmodium intortum and Gajanus cajan. Application of the various green manures except that from Desmodium did not significantly affect the coffee growth. The application however, significantly reduced primary extension and leaf area of coffee plants. Application of the various green manures significantly depressed the coffee yields. It was concluded that application of green manures to coffee plants could only be beneficial during the first year after coffee establishment but the green manures may not be able to supply adequate plant nutrients. They however improved the soil physical characteristics. The second experiment was to study the effect of intercropping coffee plants, during the establishment phase, with the following fruits: pawpaws (Garica papaya), passion fruit (Passiflora edulis), apples (Malus (xxiii) pumila), oranges (Citrus sinesis), bananas (Musa sapentium), guava (Psidium guajava) , avocadoes (Persea americana), loquats (Eriobotrya japonica) and macadamia (Macadamia temifo/ia). Banana and guava intercrops significantly depressed coffee plant height, plant stem diameter and yield components (number of primaries and nodes per primary). However, the depression did not affect the clean coffee yields. The other fruit tree intercrops did not significantly affect coffee tree growth or clean coffee yields or the bean quality. The third experiment was to study the effects of intercropping mature arabica coffee CV SL 28 during the change of cycle phase, with beans (Phaseolus vulgaris), cowpea (Vigna unguiculata), Irish potatoes (Solanum tuberosum), tomatoes (Lycopersicon esculentum), sweet potatoes (Ipomea batatas) and garden peas (Pisum sativum). The results showed that the food intercrops did not significantly affect coffee tree growth and coffee bean yield and quality. Yields of the intercrops were also not affected by coffee plants during the first year after change of cycle. However, during the second year, the yields were reduced due to the heavy canopy especially under high density. Although there was a yield advantage during the two years of change of cycle, it was uneconomical to intercrop during the second year. The various fruit and food crops evaluated are suitable intercrops in coffee. Intercropping food crops during change of cycle phase should be limited to the first year only.