Manuel Tejada

Effects of the application of a compost originating from crushed cotton gin residues on wheat yield under dryland conditions

The influence of four doses of a compost originating from residues of crushed cotton gin on wheat (Triticun aestivum cv. Cajeme) in dryland conditions (Guadalquivir Valley, Andalusia, Spain) has been studied. The results obtained in this study showed that this compost is of great agricultural interest product because of its organic matter content. The application of this byproduct to the soil resulted in an increase in soil microbial activity, structural stability and soil porosity. Mineralization of organic matter produced a higher concentration of NO3−–N in soil, and an increase on the yield parameters and grain yield in both seasons.

Evolution of soil biological properties after addition of glyphosate, diflufenican and glyphosate+diflufenican herbicides.

The aim of this paper was to study in laboratory the degradation and the effects on biological properties in two soils after the addition of glyphosate, diflufenican and glyphosate+diflufenican. One hundred grams of sieved soil (<2mm) were mixed with (i) 13mL of Zarpa (16% glyphosate and 4% diflufenican) prepared in a water solution of 1L (0.52g of glyphosate and 2.08g of diflufenican), (ii) 5.2mL of Round up (40% glyphosate), prepared in a water solution of 1L (0.52g of glyphosate), and (iii) 1.19mL of Brodal (43.5% diflufenican), prepared in a water solution of 1L (2.08g of diflufenican). Soil samples were collected after 0, 1, 5, 10, 15, 30, 60, 120 and 180d of incubation and analyzed for microbial biomass-C and dehydrogenase, urease, beta-glucosidase, phosphatase, arylsulphatase activities and glyphosate and diflufenican contents. At the end of the experiment, in the clayey texture soil the glyphosate and diflufenican contents were higher 50% and 30.7%, respectively, for the glyphosate+diflufenican treatment compared to glyphosate and diflufenican treatments, respectively. In the sandy loam texture soil the glyphosate and diflufenican contents were higher (38.9% and 39.4%, respectively) when the glyphosate and diflufenican were added as Zarpa than Round up or Brodal. The application of glyphosate+diflufenican mixture to soil increased the toxic effects of both herbicides in the soil biological activity and the individual soil persistence of each herbicide.

Study of composting of cotton residues

A study on the composting of residues of cotton gin previously crushed or uncrushed is presented in this work. A multifactor analysis of correlation for each one of the treatments revealed that the final results obtained during the composting process of cotton residuals were very different according to whether the residues were crushed or uncrushed. Generally, the highest final values of macronutrients and micronutrients obtained were found when the composting process was carried out with the crushed residuals.

Use of organic amendments as a bioremediation strategy to reduce the bioavailability of chlorpyrifos insecticide in soils. Effects on soil biology

The sorption capacity of both an organic municipal solid waste by-product (MSW) and a cow manure (CM) in a soil polluted with chlorpyrifos, as well as its effect on soil microbial activity, and weight, reproductive parameters and glutathione-S-transferase activity of two earthworm species (Eisenia fetida and Lumbricus terrestris) were studied. Chlorpyrifos was added at the recommended application rate (5 L ha(-1); 768 mg chlorpyrifos kg(-1)) and treated with MSW at a rate of 10% and CM at a rate of 5.8% in order to apply the same amount of organic matter to the soil. An unamended polluted soil was used as control. Earthworm cocoon number, average weight of cocoon, and number of juveniles per cocoon were measured after 30 days of incubation, whereas soil enzymatic activities, earthworm weight, and glutathione-S-transferase activity of earthworms were measured after 3, 45 and 90 days. Soil enzymatic activities, reproductive and glutathione-S-transferase activity in both worms decreased in polluted soil. The inhibition percentage of soil enzymatic activities, reproductive and glutathione-S-transferase activity in both worms was lower in MSW-amended soil than for CM-amended soil. The toxic effect of chlorpyrifos on E. fetida was lowest compared to L. terrestris. This suggested that the addition of organic wastes with higher humic than fulvic acid concentration is more beneficial for remediation of soils polluted with chlorpyrifos.

Effects of foliar application of a byproduct of the two-step olive oil mill process on rice yield

The main objective of this work is to study the effects of foliar fertilization with a byproduct of the two-step olive oil mill process at different dose on rice (Oriza sativa cv. Puntal) production and quality in Villafranco del Guadalquivir, near to Sevilla city (Andalusia, Spain). The obtained results show that the foliar fertilization with a byproduct rich in humic substances (but also containing macro- and micronutrients) increased the leaf concentration of micronutrients Fe, Cu, Zn and Mn, and macronutrients N and K uptake by plants. Highest values of chlorophyll A, B and carotenoids were found in the plots foliar fertilized, which presumably favoured photosynthesis. Foliar application of the byproduct gave significant increases in grain protein concentration of about 22%, grain starch concentration of about 5%, grain yield of about 4% and a significant rice yield of about 6%.

Evaluation of soil biological activity after a diesel fuel spill

Diesel fuel contamination in soils may be toxic to soil microorganisms and plants and acts as a source of groundwater contamination. The objective of this study was to evaluate the soil biological activity and phytotoxicity to garden cress (Lepidium sativum L.) in a soil polluted with diesel fuel. For this, a diesel fuel spill was simulated on agricultural soil at dose 1 l m(-2). During the experiment (400 days) the soil was not covered in vegetation and no agricultural tasks were carried out. A stress period of 18 days following the spill led to a decrease in soil biological activity, reflected by the soil microbial biomass and soil enzymatic activities, after which it increased again. The n-C(17)/Pristine and n-C(18)/Phytane ratios were correlated negatively and significantly with the dehydrogenase, arylsulphatase, protease, phosphatase and urease activities and with the soil microbial biomass during the course of the experiment. The beta-glucosidase activity indicated no significant connection with the parameters related with the evolution of hydrocarbons in the soil. Finally, the germination activity of the soil was seen to recover 200 days after the spill.

Agricultural use of leachates obtained from two different vermicomposting processes

The objective of this paper was to investigate the possible agricultural use of the vermicomposting process leachates. Two leachates coming, respectively, from the vermicomposting of cow dung (SCD) and the vermicomposting of green forages (SGF), as well as solution of Hewitt (C) were used at a dose of 1 ml 500 ml(-1) in the foliar fertilization of tomato plants. Treatments were applied 30, 60 and 90 days after planting (DAP). The obtained results showed that foliar fertilization with SCD and SGF increased the morphological and chemical parameters on tomato crop with respect to the plants receiving foliar treatment with SH and C, possibly due to the humic substances content in SCD and SGF. The higher content of humic substances in SGF with respect to the SCD are possibly the responsible of the higher chlorophyll contents observed in the plants receiving the former treatment. This aspect possibly promoted an increase in plant photosynthesis and therefore an increase in fruit quality.

Application of MCPA herbicide on soils amended with biostimulants: short-time effects on soil biological properties.

In this paper we studied in the laboratory the effect of MCPA herbicide at a rate of 1.5lha(-1) (manufactures rate recommended) on biological properties of a Plagic Antrosol amended with four biostimulants (WCDS, wheat condensed distillers soluble; PA-HE, hydrolyzed poultry feathers; CGHE, carob germ enzymatic extract; and RB, rice bran extract). Seven hundred grams of soil were mixed with WCDS at a rate of 10%, CGHE at a rate of 4.7%, PA-HE at a rate of 4.3%, and RB at a rate of 4.4%, respectively, in order to applying the same amount of organic matter to the soil (16.38 g organic matter). An unamended polluted and amended non-polluted soil were used as control. For all treatments, the soil ergosterol, dehydrogenase, urease, and phosphatase activities were measured at two incubation times (0 and 60 d). The 16S rDNA-DGGE profiles in all treatments were determined at the beginning and end of the incubation period. The results indicated that at the end of the incubation period and compared with the control soil, the dehydrogenase, urease and phosphatase activities and ergosterol decreased 39.3%, 20%, 15.7% and 56.5%, respectively in the non-organic amended polluted soil. The application of organic matter to unpolluted soil increased the enzymatic activities and ergosterol. However, this stimulation was higher in the soil amended with RB, followed by PA-HE, WCDS and CGHE. The application of herbicide in organic-amended soils decreased the enzymatic activities and ergosterol content. However, this decrease was lower than for the non-amended herbicide polluted soil. Possibly the low molecular weight protein content easily assimilated by soil microorganisms and the adsorption capacity of humic substances are responsible for less inhibition of these enzyme activities and soil ergosterol. The 16S rDNA-DGGE profiles indicated that herbicide did not negatively affect soil bacterial biodiversity.

Organic amendment based on vermicompost and compost: differences on soil properties and maize yield

The objective of the present study was to study the effect of two vermicomposts [animal (VCD) and vegetal origin (VGF)] and a cotton gin compost (C) at rates of 1780 and 3560 kg fresh organic matter ha−1 for 3 years on an Typic Xerofluvent located near Seville (Spain) on soil biological properties, nutrition (leaf N, P and K concentration, pigments and soluble carbohydrate concentrations) and yield parameters of maize (Zea mays cv. Tundra) crop. All organic waste materials had a positive effect on the soil biological properties, plant nutrition and crop yield parameters, although at the end of the experimental period and at the high organic matter rate, the soil microbial biomass and dehydrogenase, urease, β-glucosidase, phosphatase and arylsulfatase activities increased more significantly in the VCD-amended soils (86.4, 85.8, 94.5, 99.3, 70.1 and 63.8%, respectively) respect to the control soil, followed by VGF-amended soils (84.8, 80.6, 92.7, 99.1, 68.3 and 61.6%, respectively) and CC-amended soils (80.5, 75.9, 89.7, 99, 65.7 and 59.9%, respectively). Leaf N, P and K contents and pigments and soluble carbohydrate contents were highest in VCD-amended soils, followed by VGF and CC treatments. Compared with the control soil, the application of VCD in soils at high doses increased the crop yield parameters, followed by VGF and CC treatments. This may have been due to a greater labile fraction of organic matter in the VCD than the VGF and CC, respectively.

Relationships between biological and chemical parameters on the composting of a municipal solid waste.

The aim of this work was to study the combined relationships between biological and chemical parameters with the humification index (HI) and degree of polymerisation (DP) during the composting of a municipal solid waste. During the composting, biological parameters increased during the first 15 days. After the second week, the dehydrogenase, urease, beta-glucosidase, phosphatase and arylsulphatase activities decreased 64%, 50.1%, 49.6%, 24.1% and 58.3%, respectively, compared with their initial values, possibly due to the decreasing of the water-soluble carbon content (WSC). The WSC contents decreased possibly due to the degradation of the microorganisms as carbon and energy sources. The HI increased (66% compared to the initial values) indicating an increase in the structural complexity of the humic substances. The factorial analysis indicates a relationship between the biological properties, WSC and HI and DP. The linear regression analysis indicates the high correlation coefficients found between the HI and DP with chemical and biological properties, and therefore, it can be concluded that combination of chemical and biological parameters can be used to determine the compost maturity.