Abstract

ABSTRACT The large production of sewage sludge (SS), especially in large urban centers, has led to the suggestion of using this waste as fertilizer in agriculture. The economic viability of this action is great and contributes to improve the environment by cycling the nutrients present in this waste, including high contents of organic matter and plant nutrients. This study evaluated the chemical and biochemical properties of Dystrophic and EutroferricLatossolos Vermelhos (Oxisols) under corn and after SS application at different rates for 16 years. The field experiment was carried out in Jaboticabal, São Paulo State, Brazil, using a randomized block design with four treatments and five replications. Treatments consisted of control - T1 (mineral fertilization, without SS application), 5 Mg ha-1 SS - T2, 10 Mg ha-1 SS - T3, and 20 Mg ha-1 SS - T4 (dry weight base). The data were submitted to variance analysis and means were compared by the Duncan test at 5 %. Sewage sludge increased P extracted by resin in both theLatossolos Vermelhos, Dystrophic and Eutroferric, and the organic matter content in the Dystrophic Latossolo Vermelho. The waste at the rate 20 Mg ha-1 on a dry weight basis promoted increases in acid phosphatase activity in Eutroferric Latossolo Vermelho, basal respiration and metabolic quotient in DystrophicLatossolo Vermelho. The rate 20 Mg ha-1 sewage sludge on a dry weight basis did not alter the soil microbial biomass in both the Latossolos Vermelhos; in addition, it improved corn yields without inducing any symptoms of phytotoxicity or nutrient deficiency in the plants.

Highlights

  • The large production of sewage sludge (SS), mainly in urban areas, has led to the alternative suggestion of using it as fertilizer in farming activities

  • Microbial biomass, basal respiration, metabolic quotient and activities of enzymes involved in C, N, P and S cycles have been used to assess SS application in soils (Garcia-Gil et al, 2000)

  • This study evaluated chemical and biochemical properties of two Latossolos Vermelhos, Dystrophic and Eutroferric, under corn cultivation and after 16 years of annually sewage sludge application in different rates

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Summary

Introduction

The large production of sewage sludge (SS), mainly in urban areas, has led to the alternative suggestion of using it as fertilizer in farming activities. This option is economically highly viable, for protecting the environment by cycling the elements contained in the waste, which has high amounts of organic matter and nutrients for crop plants. Organic material and nutrients of SS play an important role in sustaining crop yields and soil fertility (Ceolato, 2007) It can be considered a highly beneficial residue for use in agriculture as soil physical, chemical and biological conditioner due to the high organic matter content and the presence of plant nutrients (Melo et al, 1994). Microbial biomass, basal respiration, metabolic quotient (qCO2) and activities of enzymes involved in C, N, P and S cycles have been used to assess SS application in soils (Garcia-Gil et al, 2000)

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