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Free living diazotrophic bacteria are known to enrich nitrogen of organic matter sources. In this paper we report of experiments using rock biofertilizers mixed with two types of organic matter (earthworm compound and ice cream waste) inoculated with free living diazotrophic bacteria. The earthworm compound and P and K biofertilizers were mixed to form substrates S 1 (earthworm compound 3 dm 3 ? PK biofertilizer 1 dm 3 and waste ice cream 1 dm 3 ); S 2 (earthworm compound 2.5 dm 3 ? PK biofertilizer 1.5 dm 3 and waste ice cream 1 dm 3 L) and S 3 earthworm compound 2.0 dm 3 ? PK biofertilizer 2.0 dm 3 and waste ice cream 1 dm 3 ), and subsequently inoculated (100 mL pot -1 ) with 3 free living diazotrophic bacteria isolated from different Brazilian soils. The control was an uninoculated earthworm compound. Samples were collected at various incubation time (0; 15; 30 and 45 days) and analyzed for total N. Total N concentrations were highest in S 1 , S 2 and S 3 substrates at 34, 27 and 29 days, respectively. The isolate NFB 1001 increased total N in all substrates and the best results were obtained at 34 days in S 1 substrate which contained the highest amount of earthworm compound. The isolates promoted a decline in N content after 30 days of growth, indicating the best time to produce the organic biofertilizer. The organic biofertilizer enriched in nitrogen by free living diazotrophic bacteria is of relevance to organic agriculture.

A quantificação da deposição de serapilheira e o acúmulo de manta orgânica são etapas importantes dos estudos de ciclagem de nutrientes. Com esse fim, objetivou-se quantificar a deposição de serapilheira e o acúmulo de manta orgânica em um povoamento de Sabiá (Mimosa caesalpiniifolia Benth.), no campo experimental pertencente à Empresa Pernambucana de Pesquisa Agropecuária - IPA, Itambé, PE. Para quantificação da serapilheira foram utilizados 20 coletores de madeira de 0,50 x 0,50 x 15 cm, à distância do solo de 30 cm, distribuídos sistematicamente na área. O material depositado foi coletado mensalmente no período de outubro/2000 a setembro/2001. O material colhido em cada coletor foi separado em folhas, galhos, flores, frutos e miscelânea. A manta orgânica não decomposta sobre o solo foi amostrada, ao acaso, nas proximidades da caixa coletora, obtendo-se 20 amostras mensais. De cada amostra foi retirado o material contido numa área de 30 x 30 cm. O material colhido foi separado em folhas, flores, frutos, miscelânea e galhos. As amostras foram levadas à estufa a 60 º C no período de 48 horas até peso constante. A deposição mensal de serapilheira e frações folha e legume ocorreu em outubro, provavelmente devido ao início do período seco. A deposição e o estoque de serapilheira foram estimados em 7830,44 kg.ha-1.ano-1 e 8906.9, kg.ha-1, respectivamente, com a fração folha dominando. A fração folha apresentou os maiores teores de nutrientes.

Although signal exchange between legumes and their rhizobia is among the best-known examples of this biological process, most of the more characterized data comes from just a few legume species and environmental stresses. Although a relative wealth of information is available for some model legumes and some of the major pulses such as soybean, little is known about tropical legumes. This relative disparity in current knowledge is also apparent in the research on the effects of environmental stress on signal exchange; cool-climate stresses, such as low-soil temperature, comprise a relatively large body of research, whereas high-temperature stresses and drought are not nearly as well understood. Both tropical legumes and their environmental stress-induced effects are increasingly important due to global population growth (the demand for protein), climate change (increasing temperatures and more extreme climate behavior), and urbanization (and thus heavy metals). This knowledge gap for both legumes and their environmental stresses is compounded because whereas most temperate legume-rhizobia symbioses are relatively specific and cultivated under relatively stable environments, the converse is true for tropical legumes, which tend to be promiscuous, and grow in highly variable conditions. This review will clarify some of this missing information and highlight fields in which further research would benefit our current knowledge.

Experiments were conducted to evaluate the effectiveness of biofertilizers produced from phosphate and potash rocks mixed with sulfur inoculated with Acidithiobacillus oxidizing bacteria on sugarcane yield and their effects on some chemical attributes of a Brazilian tableland soil. The experiment was arranged in a completely randomized factorial design 2 9 4 9 3 + 1, with four replicates. Two varieties of sugarcane, four rates of three sources of P and K (apatite + biotite, P + K biofertilizers with Acidithiobacillus, and soluble fertilizers-triple superphosphate and potassium chloride) were tested. A control without P and K fertilization was applied. A significant reduction in soil pH was observed with biofertilizers, especially when applied at higher rates, although no harmful effect on sugarcane yield was observed. Available P and K and exchangeable Ca and Mg increased with biofertilizer application compared to mineral fertilizers and P and K rocks. Biofertilizers may be used as an alternative source of P and K for sugarcane grown in soils with low available P and K.

The objective of this study was to determine ruminal degradability of the dry matter (DM) and crude protein (CP) of 10 varieties of spineless cactus (Opuntia spp.) grown in north-eastern Brazil. Two ruminally fistulated steers were used in a randomized complete block design. Ash, CP, acid detergent fiber, and acid detergent lignin levels ranged from 10.4 to 13.3 %, 6.2-7.7 %, 19.8-24.8 % and 3.4-5.4 %, respectively. Relative to the other cactus varieties, Redonda had the highest (P < 0.05) in situ soluble DM fraction and effective DM degradability. No differences in effective DM degradability were observed between the other cactus varieties. In situ soluble CP fraction ranged from 1.7 % of CP for the 69 IPA ⁄ UFRPE variety to 11.1 % of CP for the Gigante variety. Slowly degradable CP fraction and its rate of degradation were similar among the cactus varieties (average 90 % of CP and 9 % h )1 , respectively). The cactus variety 69 IP ⁄ UFRPE had a lower (P < 0.05) effective ruminal CP degradability (ECPD) than the other varieties, which had a similar ECPD (average 66 % of CP). It was concluded that differences in ruminal degradability exist between cactus varieties, with more variations observed for ruminal DM than for CP degradability.

O trabalho foi realizado na Estação Experimental de Itambé, PE, para avaliar a distribuição da biomassa e nutrientes em povoamentos de Mimosa caesalpiniaefolia Benth. Foram estudados dois povoamentos, em solo e topografia similares com oito e 11 anos de idade, nos espaçamentos de 3,0 x 3,0 m e 4,5 x 4,5 m, respectivamente. A biomassa foi determinada para cada componente aéreo. As amostras de folhas, galhos, cascas e fuste foram coletadas e analisadas quimicamente. A biomassa total encontrada foi de 66,22 e 80,78 t/ha, nos povoamentos I e II, respectivamente. O material lenhoso (galhos e lenho) representou 96,52 e 97,98% da biomassa total, nos povoamentos I e II. A distribuição de biomassa nos povoamentos I e II foi, respectivamente; de galhos (44,99 e 53,40%), fuste (51,53 e 44,58%), casca (2,39 e 1,40%) e folhas (1,10 e 0,62%). A ordem de concentração de nutrientes nos dois povoamentos, em todos os componentes da parte aérea, de modo geral, obedeceu à seguinte ordem decrescente: nitrogênio > cálcio > potássio > magnésio > enxofre > fósforo.

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