Resumo

SERRI, Dannae Lilia; FAGGIOLI, Valeria Soledad  e  LORENZON, Claudio Antonio. Fósforo del suelo: calidad del rastrojo y descomposición microbiana bajo diferentes contenidos hídricos. Cienc. suelo [online]. 2017, vol.35, n.2, pp.239-248. ISSN 1850-2067.

Crop residues and stubble are important agroecosystem resources, but there is scarce information on the processes of microbial nutrient release and immobilization related to plant material quality and environmental conditions. The objective of this work was to evaluate the effect of different soil moisture contents and plant residue quality on biochemical processes related to soil phosphorus (P) dynamics. A bioassay was performed and the treatments were: a) Crop residues: Control, without plant residue (T_e); Vicia villosa residue (V); Triticum aestivum L. residue (T) and V. T, corresponding to the combination of V and T; and b) Soil moisture: field capacity (CC), 75% CC and wilting point (PMP). After 10, 20, 40 and 60 days of the experiment we measured MS (dry matter), P_R (P of residue), C:N_R (C:N of residue) and C:P_R (C:P of residue) in plant residue. In the soil we quantified: C:N (C:N_S), microbial respiration (RM), fluorescein diacetate hydrolysis (FDA), phosphatase acid (FA), P (P_S), microbial biomass P (PBM) and microbial biomass C (CBM). The results showed that although in the course of the experiment the soil water content affected plant material decomposition, the stubble quality had a greater influence on the microorganism activity. In general, the greatest decomposition and biological activity was observed in CC. Regardless of the water content, the incorporation of plant tissues in soil increased FDA and RM; and FA and P_S were higher when V was added. The released P was assimilated by C_BM at 20 days, but was followed by a mineralization phase. These results allowed to assert the importance of the plant material quality on the biochemical functions related to the stubble decomposition and crop residues, and soil phosphorus dynamics.

Palavras-chave : Stubble quality; Microbial activity; Phosphorus mineralization and phosphorus immobilization.

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