EDAPHICAL CHARACTERISTICS OF THREE VEGETABLE CACTUS PEAR ORCHARDS (OPUNTIA FICUS-INDICA) FERTILIZED WITH HIGH AMOUNTS OF DAIRY MANURE AT MILPA ALTA, MEXICO

Vegetable cactus pear or “nopalitos” production in Milpa Alta is characterized by the use of high rates; up to 600 ton/ha of fresh manure as organic fertilizer. Due to the reduction of the number of stables in Milpa Alta and its surroundings, growers compensate the lack of organic fertilizer with chemical fertilizers. A study of the chemical and physical characteristics and properties of the soil of three nopal plantations of Milpa Alta was carried out. The following results were obtained: the textural class was classified as sandy loam, pH was slightly acid and soils were rich in organic matter (3.04 to 4.53%), phosphorous content was extremely high: 239.12, 235.54 and 228.19 ppm. Mg++ concentrations ranged from 4.70 cmol(+) kg-1 to 5.37% cmol(+) kg^-1. As for calcium 7.78 cmol(+) kg^-1 to 9.18 cmol(+) kg^-1. The quantity of potassium (K+) found in the plots varied from 1.88 cmol(+) kg^-1 to 3.76 cmol(+) kg^-1 whereas for Na 2.02 to 2.75 ppm. It seems that due to the volcanic origin of the soils and the high rates of manure the phosphorous is not a restrictive element for nopal production. Nopal cultivation is complex and for the total understanding of the system it should be considered not only the soil, but also management, social and economic factors.