abstract background: the recovery of areas impacted by mining activities is a major challenge and requires knowledge of how the biological and biochemical processes of the soil as well as the establishment of plant species are affected by mining residue. in this work, the influence of deposition of iron mining mud and tailings on soil biochemical attributes and the initial development of tree seedlings was studied in a simulated event in the greenhouse. pots (n = 27) with natural soil (2.0 kg) received deposition (280 ml) of iron mining mud or tailings and by three-month was cultivated with urochloa decumbens. at the end of this period, part of the pots was sampled and the soil biochemical activities were evaluated. then tree seedlings (schinus terebinthifolius and eremanthus incanus) were planted and cultivated for a year, when then shoot (sdw) and roots (rdw) dry weight were evaluated. results: deposition of iron mining mud and tailings did not affect microbial biomass carbon or basal soil respiration, however both conditions reduced (p < 0.05) β-glucosidase activities by up to 30%, and the easy extractable glomalin by about 19%. in addition, the mud deposition reduced (p < 0.05) the sdw and rdw of s. terebinthifolius by about 21% and 24%, respectively. nevertheless, uruchloa decumbens and eremanthus incanus had no variation in dry weight production between treatments, so they have good ability to grow settle in soil affected by mining residue. conclusion: this study shows that the sequential planting of u. decumbens and e. incanus can be an alternative for use in environments with deposition of iron mining tailings.

RESUMO Sistemas integrados de produção agropecuária (SIPA) com consórcios na fase pastagem promovem alterações na dinâmica de atributos dos solos, entre eles a atividade enzimática. Objetivou-se avaliar as atividades microbiana e enzimática do solo, após implantação de SIPA com aumento da diversidade de plantas na fase pastagem. O estudo consistiu no cultivo de soja na safra e pasto com diferentes níveis de diversidade na safrinha: muito baixa - Urochloa brizantha cv. BRS Paiaguás cultivado solteiro sem entrada de animais; baixa - Paiaguás em cultivo solteiro; média - Paiaguás e feijão caupi (Vigna unguiculata); alta - Paiaguás, feijão caupi e niger (Guizotia abyssinica); muito alta - Paiaguás, feijão caupi, niger, trigo mourisco (Fogopyrum esculentum) e nabo forrageiro (Raphanus sativus). A introdução de plantas de diferentes famílias, associadas ao pastejo, afetaram positivamente as atividades enzimáticas da fosfatase ácida, β-glicosidase e urease. Em relação aos atributos carbono da biomassa microbiana e respiração basal, não houve efeito dos tratamentos. Portanto, dentre os atributos bioquímicos do solo avaliados, as atividades de algumas enzimas do solo foram mais sensíveis em demonstrar, em curto período de tempo, os efeitos positivos do aumento da diversidade de plantas na fase de pastagem do SIPA.

ABSTRACT Integrated crop-livestock systems (ICLS) intercropped in the pasture phase promote alterations in the dynamics of soil attributes, among them the enzymatic activity. This study aimed to evaluate soil enzymatic and microbial activities, following the implementation of ICLS with increased plant diversity during the pasture phase. The study consisted of soybean cultivation at season and pasture with different diversity levels in the off-season: very low - monocropped Urochloa brizantha cv. BRS Paiaguás with no animal entry; low - monocropped Paiaguás; medium - Paiaguás and cowpea bean (Vigna unguiculata); high - Paiaguás, cowpea bean and niger (Guizotia abyssinica); very high - Paiaguás, cowpea bean, niger, buckwheat (Fogopyrum esculentum) and forage turnip (Raphanus sativus). The introduction of plants from different families, associated to grazing, positively affected the enzymatic activities of acid phosphatase, β-glucosidase and urease. In relation to microbial biomass carbon and basal respiration, there were no effects from the treatments. Therefore, among the evaluated biochemical soil attributes, the activities of some soil enzymes were more sensitive in demonstrating, in the short term, the positive effects of the increased plant variety in the ICLS pasture phase.

RESUMO A fixação biológica de nitrogênio (FBN) desempenha um importante papel no cultivo do feijão-caupi. Este estudo objetivou avaliar os teores foliares de clorofila e os componentes de produção do feijão-caupi submetido à inoculação combinada de rizóbios em solo de Cerrado. O experimento foi realizado em condições de campo, de dezembro de 2014 a março de 2015, em Rondonópolis, Mato Grosso, utilizando delineamento em blocos casualizados, com dez tratamentos e três repetições. Foram testadas as estirpes MT8 e MT15 (ambas de Rhizobium tropici), MT16 (R. leguminosarum), BR3267 (Bradyrhizobium japonicum), as combinações das estirpes MT8+MT15, MT8+MT16, MT15+MT16 e MT8+MT15+MT16, adubação nitrogenada (70 kg ha-1 de N-ureia) e controle absoluto (sem inoculação de rizóbios e sem adubação nitrogenada). Os dados foram submetidos à análise de variância e as médias foram comparadas por contraste ortogonal e teste F (p≤0.05). Foram avaliados o índice de clorofila Falker (aos 40 e 60 dias após a semeadura), número e massa seca de nódulos (aos 40 dias após a semeadura), número de vagens por planta, rendimento de grãos, concentração e o acúmulo de nitrogênio nos grãos e a proteína bruta. O número de vagens por planta foi incrementado em 33,6% na combinação MT8+MT15. O mesmo efeito foi observado para o rendimento de grãos, que apresentou aumento de 8,7%, 13,8% e de 16,7% nas combinações MT8+MT16, MT15+MT16 e MT8+MT15, respectivamente. O acúmulo de nitrogênio nos grãos foi incrementado em 42,7% com a inoculação da estirpe MT15. O feijão-caupi responde positivamente à inoculação combinada de estirpes de rizóbio.

ABSTRACT Biological nitrogen fixation (BNF) plays an important role in the cowpea cultivation. This study aimed to assess the foliar levels of chlorophyll and the yield components of cowpea subjected to combined inoculation of rhizobia in Cerrado soil. The experiment was carried out in field conditions, from December of 2014 to the march of 2015, in Rondonópolis, Mato Grosso, using randomized block design with ten treatments and three replicates. Were tested the single strains MT8 and MT15 (both of R. tropici), MT16 (R. leguminosarum), BR3267 (Bradyrhizobium japonicum), the strains combinations MT8+MT15, MT8+MT16, MT15+MT16, and MT8+MT15+MT16, nitrogen fertilization (70 kg ha-1 of N-urea), and absolute control (without inoculation of rhizobia and without nitrogen fertilization). Data were subjected to analysis of variance and the averages were compared by orthogonal contrast and F test (p≤0.05). Were assessed the Falker chlorophyll index (at the 40 and 60 days after sowing), number and dry matter of nodules (at the 40 days after sowing), number of pods per plant, grains yield, the concentration and accumulation of nitrogen in grains, and crude protein. The number of pods per plant was increased 33.6% in the combination MT8+MT15. The same effect was observed for the yield grain, which presented an increase of 8.7%, 13.8%, and 16.7% in the combinations MT8+MT16, MT15+MT16, and MT8+MT15, respectively. The nitrogen accumulation in the grains increased 42.7% with the inoculation of MT15 strain. The cowpea responds positively to the usage of combinations of rhizobia strains.