Carolina Etienne de Rosália e Silva Santos

Plant and soil characteristics affected by biofertilizers from rocks and organic matter inoculated with diazotrophic bacteria and fungi that produce chitosan

The aim of this study was to evaluate the effectiveness of a mixed biofertilizer with phosphate and potash rocks (PK biofertilizer) combined with an earthworm compound inoculated with free living diazotrophic bacteria and Cunninghamella elegans, fungi that produces chitosan, on cowpea nodulation, biomass yield and nutrient uptake. The effects of some chemical attributes from an acidic soil of the Brazilian Northeast were also studied. The treatments were as follows: a) biofertilizer enriched in N by free living diazotrophic bacteria(NPKB), applying crustaceous chitosan (ChCru) at a rate 2 mg mL -1 ; b) NPKB and ChCru at a rate 4 mg mL -1 ; c) NPKB and ChCru at a rate 6 mg mL -1 ; d) NPKB and fungi chitosan (ChFu, 2 mg mL -1 ); e) NPKB+C. elegans (NPKP); f) NPKB without chitosan; g) mineral fertilizers (NPKF); and h) control without NPK fertilizer and chitosan. Biofertilizer treatments increased cowpea nodules biomass, shoot biomass, and total N, P, and K in the shoots. The largest increase was obtained with ChCru, and the highest rate was obtained with NPKP. Furthermore, biofertilizers reduced soil pH and increased the total N and available P and K. These results reveal the potential of rock biofertilizer mixed with earthworm compound inoculated with free living diazotrophic bacteria and C. elegans (fungi chitosan) for plant production and nutrient uptake. The biofertilizer may be an alternative for NPK fertilization that slows the release of nutrients, favoring longterm soil fertility.

Rendimento da alface e atributos químicos de um Latossolo em função da aplicação de biofertilizantes de rochas com fósforo e potássio

Production of rock biofertilizers is a practical process which reduces energy consumption and increases nutrients availability in soils. A field experiment was carried out applying phosphate biofertilizer (PB) and potash biofertilizer (KB) from rocks plus sulfur with Acidithiobacillus, applied in different rates, comparing with the mineral fertilizers simple superphosphate (SFS) and potassium chloride (KCl), on yield of lettuce (cv. Crespa-Grand Rapids), in two consecutive crops and in soil chemical attributes (pH, and available P and K). A control treatment was added without P and K (P0K0). In the two consecutive crops the biofertilizers BP, BK, and chemical fertilizers SFS and KCl were effective on lettuce yield. In the first crop the best results were obtained with the treatments SFS700 BK90, SFS700 BK60, and in the consecutive crop applying the treatments BP700 BK90, SFS700 BK60 and SFS700 BK90. In the two crops the positive response of the PK biofertilizers and PK mineral fertilizers was evident. Residual effect was observed when the treatment BP1050 BK90 was applied. Soil pH was not affected by application of PK biofertilizers plus worm-compound, increasing available P and K, especially for available P in the consecutive crop. The PK rock biofertilizers, plus worm-compound, may be applied as an alternative to PK mineral soluble fertilizers.

Eficiência e efeito residual de biofertilizantes de rochas com PK e enxofre com Acidithiobacillus em alface

Production of rock biofertilizers is a practical process with reduction of energy consumption and increasing nutrients availability in soils. To evaluate the agronomic efficiency and the residual effect of P rock biofertilizer (PB) and potash rock (KB), compared to simple superphosphate (SSP) and potassium chloride (KCl), a field experiment with two consecutive lettuce crops (cv. Grand Rapids) was carried out in a soil at Cariri (Ceara, Brazil), from August to September 2005. The mineral fertilizers were applied in the levels recommended for lettuce (SSP and KCl), and the biofertilizers in three levels (PB1 and KB1 half of recommended levels; recommended levels PB2 and KB2 and 150% the recommended level PB3 and KB3 for SSP and KCl) and a control treatment with no P and K (P0K0). The experimental design was a factorial 52 in the randomized block, with four replicates. There was similar performance of the PK rock biofertilizers compared to the mineral fertilizers, especially when the level BP2BK3 was applied. The consecutive crop showed residual effect on lettuce yield (fresh shoot biomass), height, number of leaves, commercial evaluation, and P and K accumulation on shoot dry biomass. The results suggest that P and K rock biofertilizers may be used as an alternative in mineral fertilization.

Inoculation of plant-growth-promoting rhizobacteria in Myracrodruon urundeuva Allemão supports in tolerance to drought stress

ABSTRACT This study evaluated the influence of Azospirillum lipoferum on the growth of Myracroduon urundeuva (Anacardiaceae) plants under drought stress, by means of biometric, physical–chemical and biochemical parameters. The association of A. lipoferum with the roots of the plants provided increases of 30% root length, 50% root dry weight, 34% shoot dry weight and 10% soluble protein content. The inoculated plants still maintained 5% higher leaf water potential than those not inoculated and lower membrane damage. Furthermore, the inoculated plants shown less leaf fall and dark green leaves, confirmed by maintenance of the highest levels of chlorophyl a, b and total. On the other hand, superoxide dismutase activity was significantly lower in the inoculated plants, possibly due to the induction of a non-enzymatic protective feature. In this way, the inoculation of PGPR in M. urundeuva can be an alternative for the production of plants that are more tolerant to drought stress.

Effectiveness of biofertilizer enriched in N by Beijerinckia indica on sugarcane grown on an Ultisol and the interactive effects between biofertilizer and sugarcane filter cake

To improve yield and nutrient absorption, the addition of fertilizers to provide nutrients in adequate quantities is recommended. An alternative substitution for soluble fertilizer is the use of Acidithiobacillus bacteria to produce rock biofertilizer that is then mixed with organic matter inoculated with diazotrophic bacteria (Beijerinckia indica) for N enrichment. This study evaluates the effectiveness of biofertilizer on nutrient uptake and its interaction with sugarcane filter cake in field-grown sugarcane on an Ultisol in the Brazilian rainforest region. The experiment used two NPK fertilizer treatments (biofertilizer and soluble fertilizer) applied at three rates (50, 100 and 150% of the recommended rate [RR]) and a control treatment of earthworm compost (20 t ha-1). The fertilizer treatments were applied with and without filter cake, in four replicates. Total C and N, available P and K, and exchangeable Ca and Mg in plants (upper shoots, leaves and stems) as well as soil samples were analyzed. The biofertilizer showed similar responses as did the soluble fertilizer in nutrient uptake in the different parts of sugarcane and in the soil samples. The effects of biofertilizer were enhanced by the interaction of the fertilizer treatments with sugarcane filter cake. We concluded that the biofertilizer enriched in N by inoculation with B. indica may be a viable alternative for the replacement of soluble fertilizers in sugarcane.