Effects of compost made with sludge and organic residues on bean (Phaseolus vulgaris L.) crop and arbuscular mycorrhizal fungi density

In this study we evaluated five composts prepared with two sludge: from a beverage factory and from a paper industry; they were mixture with organic residues from a pepper canned and corn stubble. Composts were tested over yield of common bean and population of arbuscular mycorrhizal (AM) fungi. Mixtures of residues and sludge were composted during four months producing a non phytotoxic material with good physical and chemical properties. Bean cultivated with the application of three composts growth higher than control (without compost). Considering the bean production it was higher in plots applied with composts 1, 2 and 5 compared with control, these show high nitrogen content. In plots applied with the five composts the number of AM fungi spores found was higher than in control. We demonstrate that the use of sludge to make compost is an interesting way to take advantage of residues and a manner to improve the soil properties, because the organic matter and minerals of waste and sludge could be transformed into compounds that could recover the soil fertility.