No presente trabalho, são relatados os resultados de seis anos de um estudo, feito sob a forma de ensaio de campo, com a finalidade de verificar a possibilidade prática da restauração da lavoura velha de café, no Estado de São Paulo com o emprego da irrigação associada a outras práticas agrícolas. Foram estudados os efeitos da irrigação em três épocas de aplicação e os efeitos das combinações fatorais de NPK (ditas dosagens), presença e ausência de esterco de curral e presença e ausência de adubação verde intercalar, utilizando o delineamento de blocos balanceados e canteiros, subdivididos, com um total de nove blocos, cada um com oito tratamentos de dez plantas, totalizando 2674 cafeeiros, inclusive as bordaduras, abrangendo a área total aproximada de 38000 metros quadrados. Foi instalado num dos melhores talhões de cafezal velho da variedade "Bourbon Vermelho", plantado há cerca de 40 anos, em terra do tipo roxa misturada, desbravada de mata virgem, na atual Estação Experimental de Botucatu, antiga Fazenda do Lageado de propriedade do Ministério da Agricultura. A produção média dos talhões nos últimos nove anos que precederam a instalação do ensaio foi de 43,2 arrobas de café beneficiado por mil pés ou cerca de 463 kg/ha. O estudo sequencial das produções médias quadrienais progressivas revela que a produção do talhão declina lentamente.This paper reports and discusses results referring to a field trial set up to study the possibilities of restoring the productivity of an old coffee plantation through irrigation and fertilization. The six year study which started in 1955, was conducted in a representative, well kept coffee grove of Bourbon variety, about 40 years old, located at the Experiment Station of Botucatu, State of São Paulo. Nine randomized blocks were used with a 2x2x2 factorial for the treatments within each block. The following treatments were compared; complete chemical fertilizer in two dosages, with and without manure, and with and without green manure as an annual intercrop. The irrigation treatment included, irrigation starting in April, starting in July, and no irrigation application was determined by soil moisture depletion, when about 70 mm were consumed from the 0-80 cm soil layer. The results showed substantial increase in production during the dry years, however the significance of this production was diminished by the biennial beating effect occurring in coffee plants. During wet years, that is, when the normal rainy period is lengthened due to unexpected early rains (after irrigation has already been carried out) production may often be reduced due to excessive leaching of needed fertilizer. Use of green manure as an annual intercrop was shown not to increase production; the same occurring with the use of organic manure in the dosage of about 20 kg every year per coffee tree (which in actuality is a group of tree to five trees originally planted in the same hole). When production of the treated plots was compared with the untreated border plot trees, an increase of about 14% was shown due to the effect of chemical fertilizer alone. However the present economical situation in Brazil does not favor the use of fertilizer on a profitable basis. Considering the success obtained in forming a new coffee plantation in places where there was before an old one, a practice which is growing in importance, it would riot be advisable to recommend the expenditure of trying to improve an old coffee plantation of the type reported
