Soil carbon stock in balsa wood after fertilization strategies

The objective of this work was to evaluate whether balsa wood plantation and its fertilization can improve soil carbon stocks. Total carbon stocks in the soil-biomass system, at 0.0-0.30 m soil depths, were evaluated under three fertilization strategies, after three and seven years, and compared with carbon stocks from native forest and degraded pasture. At the highest fertilization level, balsa wood showed a carbon stock similar to that of the native forest (65.38 Mg ha-1) and, after seven years, it increased carbon stock by 18% in the soil, and by 42% in the soil-biomass system.

Application of the bacterial strains Ruminobacter amylophilus, Fibrobacter succinogenes and Enterococcus faecium for growth promotion in maize and soybean plants

Ruminobacter amylophilus, Fibrobacter succinogenes and Enterococcus faecium have characteristics that are similar to those of plant growth-promoting bacteria and can be used to promote plant development and reduce production costs. These bacteria were isolated from fistulated ruminants and are gram-negative, anaerobic or facultative anaerobic. These bacteria are frequently used to increase animal productivity through the production of many enzymes responsible for the carbon cycle and the release of other nutrients by organic matter decomposition. The bacteria R. amylophilus, F. succinogenes and E. faecium have growth promotion abilities, such as phosphorus solubilization, nitrogen promotion, and indole acetic acid and siderophore production. Tests were performed under greenhouse conditions with soybean and maize crops with five treatments and six replications. The first treatment was the control (without inoculant); the other treatments included each species of bacteria, and there was a treatment with a mixture (mix) of the three bacteria. F. succinogenes increased the root dry mass of maize by 21.4%, as well as the nitrogen and phosphorus contents, compared to the control. R. amylophilus and E. faecium decreased the phosphorus concentration in shoots of maize, and R. amylophilus increased the soil biomass carbon by 76.39% compared to the mix under maize cultivation, while E. faecium decreased the soil biomass carbon by 56.78% compared to the mix under soybean cultivation. The present study verified that Ruminobacter amylophilus, Fibrobacter succinogenes and Enterococcus faecium presented plant growth-related abilities and could be used to improve plant development, reducing the necessity of chemical fertilizers

Soil biomass and microbial activity in soybean crop area under different cover crops and different soil correction systems

The objective of this work was to evaluate soil biomass and microbial activity and soybean yield under different limestone and gypsum doses and different cover crops. The experiment was carried out in the experimental area of ​​the Fundação de Apoio a Pesquisa Agropecuária de Chapadão, on a Dystrophic Red Latosol, using cultivar Desafio. The experiment consisted of a randomized blocks design, in a split-plot factorial scheme (3x4x3), with three replications. Plots consisted of three gypsum doses: control (without gypsum), recommended dose (2.3 Mg ha-1), and double dose (4.6 Mg ha-1). Subplots consisted of four limestone doses (2, 4, and 6 Mg ha-1) and the control (without limestone). Each block had three different cover crops: Brachiaria, Millet, and allow. The values obtained with the test revealed that brachiaria had better basal respiration in the absence of gypsum. Conversely, millet had better basal respiration in with the gypsum dose. Basal respiration, using brachiaria as cover crop, was higher at the dose of 2700 kg ha-1 of limestone. However, for the fallow and the millet, basal respiration was higher when using the highest limestone dose of 6000 kg ha-1. The variable microbial biomass showed differences between cover crops only in the absence of gypsum. Brachiaria and fallow presented the highest mean for microbial biomass. The use of millet as a cover crop together with gypsum doses increased the microbial biomass. The variables mass of 100 grains and grain yield had higher mean at the limestone dose of 6000 kg ha-1 .

Introduction of Sorghum (Sorghum bicolor (L.) Moench) green manure in rotations of head salads and baby leaf crops under greenhouse

This paper deals with the introduction in tunnel-greenhouses of sweet sorghum cultivated in short, summer cycle as green manure with the aim to amend soils with biomass grown on farm. This practice has been spreading in tunnels of Sele river Valley (Salerno, Italy) where baby leaf crops are cultivated in numerous cycles (up to 5-7) per year. Three sorghum varieties for forage or biomass (Goliath, BMR 201 and BMR 333) were cultivated in two farms at Eboli and San Marzano sul Sarno with the aims to study their responses in term of fresh and dry aboveground biomass yielded, C and N content of the biomass incorporated in soil, C balance in amended soils after one year of ordinary cash crop sequences. No differences, with regard to all the parameters measured, were pointed out among the tested varieties in each site. The sorghum cycle lasted 45 days at Eboli, yielding on average 98 and 13 t ha^-1 of fresh and dry biomass, respectively; soil biomass incorporation supplied, on average 5.8 t ha^-1 of organic carbon and 273 kg ha^-1 of total nitrogen. In the farm of San Marzano, sorghum cycle lasted 68 days, yielding 116 and 18 t ha^-1 of fresh and dry biomass, respectively; soil biomass incorporation supplied, on average 8 t ha^-1 of organic carbon and 372 kg ha^-1 of total nitrogen. After one year, the plots amended with sorghum biomass showed a soil organic carbon (SOC) concentration not different from the starting point while SOC decreased in fallow plots. At Eboli, initial SOC content was 12.3 g kg^-1, but one year later it resulted 12.3, 12.8, 12.2 and 11.3 g kg^-1 in BMR 201, BMR 333, Goliath and control plots, respectively. At San Marzano initial SOC content was 11.4 g kg^-1, but one year later it resulted 11, 12, 10.7 and 10.5 g kg^-1 in BMR 201, BMR 333, Goliath and control plots, respectively. The annual C balance put in evidence that the green manure with sorghum biomass caused SOC losses higher than those detected in fallow plots let us supposing a prime effect in boosting the soil microbial C mineralization. Only cv BMR 333 in the Eboli trial, pointed out a positive SOC change of 1.8 t ha^-1. Further studies are requested to better understand the real efficacy of sorghum cover crop in soil amendment under tunnels devoted to intensive vegetable crop sequence.