ECOLOGICAL CULTIVATION OF GREENHOUSE TOMATOES (LYCOPERSICON-ESCULENTUM MILL.) IN LIMITED BEDS FERTILIZED WITH LOCALLY PRODUCED MULCHES - EFFECTS ON GROWTH AND YIELD

Fertilization of ecological cultivating systems for producing greenhou se tomatoes with locally produced mulches was studied from 1993 to 199 5. The tomato plants were cultivated in limited growth beds filled wit h nutrient-poor substrate, consisting of farmyard manure (MM) compost, straw and soil subsequently mixed with peat and gypsum. Mulches of fr eshly cut grass or clover or a mixture of the two were placed on the s urface of the substrate to assess their value as fertilizer. Fruit yie ld, fruit quality, plant length and NPK-content of mulch materials and bed water were regularly measured. Comparisons made on four occasions during each growing season showed that the mulches containing clover produced significantly higher yield than the grass mulch and this trea tment also had the best utilization of P and K. Nitrogen utilization w as highest in beds fertilized with grass mulch, even though the yield was lower, Combined mulch of grass and clover produced intermediate yi eld and had good utilization of N, P and K. However the clover-grass m ulch seemed to have potential for higher yield than was found in the e xperiment.