Short-term effects of organic municipal wastes on wheat yield,microbial biomass,microbial activity,and chemical properties of soil

The objectives of this work were to (a) investigate the short-term effects of applications of mineral fertilizer, municipal solid waste (MSW) compost, and two sewage sludges (SSs) subjected to different treatments (composting and thermal drying) on microbial biomass and activity of soil by measuring microbial biomass C, adenosine 5′-triphosphate content, basal respiration, and dehydrogenase, catalase, urease, phosphatase, β-glucosidase, and N-α-benzoyl-l-argininamide-hydrolyzing activities and (b) explore the relationships between soil microbiological, biochemical, and chemical properties and wheat yields under semiarid field conditions by principal component analysis. The additions of MSW compost, SS compost, and thermally dried SS did not affect significantly soil microbial biomass, as compared to mineral fertilization and no amendment. However, microbial activity increased in organically amended soils, probably due to the stimulating effect of the added decomposing organic matter. Changes in soil microbiological and biochemical properties showed no significant relationships with wheat yields, probably because plant growth was primarily water-limited, as typically occurs in semiarid regions.     

Characterization of Desulfovibrio sp. isolated from some lowland paddy field soils of Burkina Faso

In a wetland ecosystem such as lowland ricefields, the anaerobic mineralization of organic matter is a key mechanism for nutrient recycling (Jørgensen 1982; Freney et al. 1982). In the process which involves several bacterial groups, sulfate reducers (Watanabe and Furusaka 1980; Widdel 1988; Ouattara and Jacq 1992; Nozoe 1997), methanogens (Asakawa and Hayano 1995; Dianou et al. 1997), sulfur and ferric ion reducers (Jacq et al. 1991) become active when the soil becomes anoxic (Amstrong 1969). Sulfate reducers are common in flooded soils (Watanabe and Furusaka 1980; Widdel 1988; Furusaka et al. 1991). Reported densities in rice soils ranged from 10³ to 10⁵ g^-1 dry soils in Asia (Watanabe and Furusaka 1980) and from 10² to 10⁹ g^-1 dry soil in Sénégal (Ouattara and Jacq 1992). Among the sulfate reducers, the “classical” Desulfovibrio species are known to oxidize typical fermentation products such as hydrogen, lactate, pyruvate, and dicarboxylic acids (Widdel 1988). So far, data on the isolation and characterization of sulfate-reducing bacterial (SRB) strains from African rice paddy field soils study have been very limited.     

Influence of phosphorus stress on ammonium uptake by maize

The effect of phosphorus (P) starvation on ammonium (NH₄) uptake was evaluated by growing single‐cross seedlings of the male progenitor of the maize double‐cross hybrid BR 201 in nutrient solution. The kinetics of NH₄ uptake were measured after P starvation and non‐starvation periods of 2, 4, 6, 8, and 10 days. The effect of P addition during the study period (resupply) was also tested. Ammonium uptake decreased 45.7% after two days of P stress compared to the fully P‐sufficient control. Ammonium uptake decreased 83.0% when P was withheld for 10 days. The decline in NH₄ uptake was partially reversed when P was resupplied during the early periods of P deficiency, but this effect diminished as the P stress increased. These results suggest that maize plants are physiologically dependent on NH₄ rather than nitrate (NO₃) when under P stress.     

AMMONIUM AND NITRATE IN SOIL AND RATOON SUGARCANE GROWN IN FUNCTION OF NITROGEN ON OXISOL

After harvest, sugarcane residues left on the soil surface can alter nitrogen (N) dynamics in the plant-soil system. In Oxisols, the nitrogen fertilizer applied had its effects on the levels of ammonium and nitrate in the soil, N concentration in the plant leaves, and on the growth and productivity of second ratoon plants. The N rates tested were of 0, 60, 120, 180, and 240 kg ha^?1. Each treatment was replicated four times. Four months after the experiment was started, ammonium and nitrate concentration in the soil, N levels in plant leaves, and plant growth were evaluated. Productivity was evaluated 11 months after the experiment was set. By increasing the content of mineral N in soil, plant growth variables reflected differences in the production of stems; however, it did not affect foliar N. The use of leaf analysis was not important to assess the nutritional status of nitrogen in the ratoon sugarcane. Nitrogen concentration in soil was affected by nitrogen fertilization, but not the N content in leaves. The rate of 138 kg N ha^?1enabled greater production of sugarcane stalks (140 t ha^?1).     

Aluminum effects on uptake and translocation of nitrogen in sorghum (Sorghum bicolor,L. Moench)

The effects of aluminum on the uptake and translocation of N in two hybrid cultivars of sorghum with differential tolerance to aluminum were studied.

Aluminum decreased the amount of N accumulated and the % of N in the aerial parts of the plants. In the roots the amount of N accumulated also decreased but the % of N increased, in both cultivars. Besides an effect on dry matter yield, Al probably reduces the uptake of N and its translocation to the aerial parts of the plant. Apparently, this impairment on N translocation resulted from Al effects on the root pressure.

Aluminum not only reduced the amount of N translocated but also changed the sap composition. The % of NO₃ ‐N decreased while the % of amino acid‐N increased suggesting an Al effect on N uptake and also on protein degradation. Asparagine and glutamine contributed about 80% of the free amino acid fraction; however, their proportions changed in presence of Al. Therefore, Al also interfered with the synthesis and/or interconversion of these amino acids.     

Spatial and temporal behavior of coffee rust in C. canephora and its effects on crop yield

European Journal of Plant Pathology - Coffee rust has been one of the main factors responsible for reducing crop yield. The management of this disease corresponds to one of the main costs in the...     

Scavengers for achieving zero formaldehyde emission of wood-based panels

This work examines the performance of three formaldehyde scavengers in wood-based panels. Sodium metabisulfite, ammonium bisulfite and urea were applied in different physical forms during particleboard production, and the resulting physico-mechanical properties (internal bond strength, thickness swelling, density and moisture content) and formaldehyde emission levels were compared. Formaldehyde content was measured using the perforator method, and formaldehyde emission was evaluated both by desiccator and gas analysis methods. The chemical reactions involved in each formaldehyde scavenging process are proposed and discussed. The tested scavengers showed distinct performances under the different emission testing conditions, which were interpreted in terms of the stability of the chemical compounds formed upon formaldehyde capture. Sodium metabisulfite proved to be an excellent scavenger for all formaldehyde methods allowing the production of particleboard panels with zero formaldehyde emission.     

Meso- and macrofauna in the soil and litter of leguminous trees in a degraded pasture in Brazil

Soil organisms comprise a large number of species that play a role in various ecosystem functions and provide valuable ecosystem services that sustain soil quality. The objective of this study was to characterize the meso- and macrofauna in soil and litter with different types of plant cover (Acacia auriculiformis A. Cunn. ex Benth., Mimosa caesalpiniifolia Benth., pasture and secondary forest) at different sampling times (dry season: June and September and rainy season: February). The faunal communities were sampled over during 15 days with a Berlese-Tullgren apparatus. The density of the total fauna ranged from 822 to 6,368 individuals m^?2 in the litter and 99 to 1,222 individuals m^?2 in the soil. The richness ranged from 9.4 to 12 in the litter and 6.4 to 8.8 in the soil. In all, 12,596 individual organisms were recovered from the soil and litter samples, and 8,012 individuals were found in the litter. Seasonal variation influenced the density and richness of the total fauna and the occurrence of functional groups, particularly the populations of microbial grazers, predators and herbivores, but this influence depended on the plant cover. Most groups that were found during the three sampling periods and in all types of plant cover belonged to two functional groups: social insects (Formicidae) and microbial grazers (Collembola). The plant cover types showed homogeneity in the distribution of the soil-litter fauna, and the development of a litter layer by leguminous tree plantations in a degraded pasture produced a higher abundance and diversity of soil fauna.     

Orchard management with small unmanned aerial vehicles: a survey of sensing and analysis approaches

Precision Agriculture - Advances in sensor miniaturization are increasing the global popularity of unmanned aerial vehicle (UAV)-based remote sensing applications in many domains of agriculture....     

Descriptive Analyses of Deficiency Symptoms in Calla Lily Plants

The objective of this work was to describe the nutrition deficiencies symptoms in calla lily (Zantedeschia aethiopica). Seedlings were maintained in complete nutrition solution and with omission of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sulfur (S), iron (Fe), boron (B), and manganese (Mn), totalizing 10 treatments. The first deficiencies symptoms appeared in plants cultivated in N omission, followed by treatments with omission of S, B, K, Fe, P, and Ca. Individual omissions of N and B prevented blooming, while S and K deficiencies resulted in production of small and greenish inflorescences with deformities. Reddish spots in leaves were observed in plants growing in solution with omission of P. Root development was affected either by omission of B or S. Death of the apical bud and formation of a “black center” in calla lily rhizome was caused by B deficiency. Nitrogen, B, and S are the most required nutrients for calla lily plants. The mineral composition of calla lily leaves is affected by nutritional deficiencies