Ignacio Mariscal-Sancho

Carbon Dioxide Emission Rates and β-Glucosidase Activity in Mediterranean Ultisols Under Different Soil Management

Abstract Soil respiration is the second-largest terrestrial carbon flux, and it has shown to be deeply affected by soil management. This article reports a field and laboratory study comparing CO2 emission rates from the soil surface and &bgr;-glucosidase activity in Mediterranean Ultisols from the Cañamero raña surface (continental detritic formations from southwest Spain) under different soil management conditions and vegetation cover: 1) soil in a cork oak grove, the climax vegetation of the studied raña surface; 2) soil in a Cistus scrubland with a 100% cover, uncultived for the past 45 years; 3) soil in a crop field that has been uncultivated for the past 35 years and with 55% of the shrub cover dominated by Cistus crispus L. and the rest covered by pasture; 4) soil in a degraded pastureland; and 5) soil in an olive grove that has been continuously cultivated for the past 65 years. We made a comparative assessment of aerobic activity in each of the soils at different times of the year. The level of degradation of natural vegetation, and therefore also the organic matter content, which decreased from Areas 1 to 5, affected the rate of CO2 emission from the soil surface. This rate was also affected by soil water content, soil temperature, and the predominance of Cistus ladanifer L. in the soil vegetation cover. In the case of the Olea europaea L. grove soil, the CO2 emission rate notably increased during autumn in years of high fruit production as a result of increased root respiration. &bgr;-Glucosidase activity was mostly, and positively, affected by organic matter content and also was negatively affected by the predominance of C. ladanifer in the vegetation soil cover.

No tillage and liming reduce greenhouse gas emissions from poorly drained agricultural soils in Mediterranean regions

No tillage (NT) has been associated to increased N2O emission from poorly drained agricultural soils. This is the case for soils with a low permeable Bt horizon, which generates a perched water layer after water addition (via rainfall or irrigation) over a long period of time. Moreover, these soils often have problems of acidity and require liming application to sustain crop productivity; changes in soil pH have large implications for the production and consumption of soil greenhouse gas (GHG) emissions. Here, we assessed in a split-plot design the individual and interactive effects of tillage practices (conventional tillage (CT) vs. NT) and liming (Ca-amendment vs. not-amendment) on N2O and CH4 emissions from poorly drained acidic soils, over a field experiment with a rainfed triticale crop. Soil mineral N concentrations, pH, temperature, moisture, water soluble organic carbon, GHG fluxes and denitrification capacity were measured during the experiment. Tillage increased N2O emissions by 68% compared to NT and generally led to higher CH4 emissions; both effects were due to the higher soil moisture content under CT plots. Under CT, liming reduced N2O emissions by 61% whereas no effect was observed under NT. Under both CT and NT, CH4 oxidation was enhanced after liming application due to decreased Al(3+) toxicity. Based on our results, NT should be promoted as a means to improve soil physical properties and concurrently reduce N2O and CH4 emissions. Raising the soil pH via liming has positive effects on crop yield; here we show that it may also serve to mitigate CH4 emissions and, under CT, abate N2O emissions.

Soil Quality Dynamics Following Long-Term Application of Poultry Manure and Sewage Sludge on Grassland

Organic manures can complement or even replace mineral fertilization of a pasture within a sustainable production system. In this article, an evaluation is made of the changes occurring in some properties related to soil quality after 7 years of applying two types of organic manures, poultry manure (PM) and sewage-sludge pellets (SP), compared those produced by normal mineral fertilization and a control. Both organic manures were effective for improving the quality of the soil surface horizon; however, PM appeared more effective in accumulating organic matter and improved more soil properties than did SP. The PM in particular improved soil aggregation, microbial development, and carbon (C) and nitrogen (N) storage in the form of organic matter. On the other hand, SP lowered soil pH and increased β-glucosidase activity. The soil water-storage capacity and conservation also increased with the application of both organic manures.

Exchange Complex Composition in Mediterranean Ultisols Under Various Types of Vegetation and Soil Uses

We studied the dynamics of texture, bulk density, exchangeable bases, acidity, and aluminum in the uppermost surface 50 cm of Mediterranean Ultisols under natural vegetation at variable degradation stages and under different soil uses in the Cañameros raña formation (southwest Spain). The areas studied included a cork oak grove (the climax vegetation in the area), a field densely covered by Cistus ladaniferus L., a field with 55% covered by Cistus crispus L. and C. ladaniferus, a field with 10% covered by bushes of the same type as the previous one, and a field with grass and occasional Cistus bushes. All of these fields with bushes were extensively cultivated with rye (Secale cereale L.) and then abandoned 45, 35, 12, and 6 years, respectively, before the study. Finally, we selected an olive grove that had been under continuous tillage for the previous 65 years. The total organic matter content decreased, starting from the virgin soil, under cork oaks, to the most heavily degraded soil (that under olive trees), whereas the bulk density increased. The total contents of exchangeable Ca, Mg, Na, and K significantly decreased, in the same trend as organic matter. In contrast, the amount of aluminum extracted by 1N KCl, AlK, remained essentially constant or even increased with increasing soil degradation. This resulted in a markedly decreased Ca/AlK ratio in the topmost 5 cm of soil, which had a strong adverse effect on crop productivity and natural plant recovery after the soils were abandoned.

Economics of applications of sugar factory lime refuse in Mediterranean Ultisols

After decades of tillage, the pH and organic matter content of frail acid soils in the west and south west of Spain have dropped to critical values severely limiting the grain and pasture yields. The aim of this work was to quantify the economic feasibility of applying sugar factory lime foam (SF) in the representative acid soils studied (Plinthic Palexerult). Yields significantly increased with liming with SF at 7.4 t ha−1. The useful life of the amendments was estimated at a minimum of nine years. The mean yield of biomass in the treated plots from cereal or a mixture of cereal and vetch in the last seven seasons was of 5306 kg dry matter ha−1. The mean biomass collected represented 2.7 times that obtained in untreated control plots and 4.7 times the mean yield of natural pasture fields. Once all the liming expenses (25 € t−1) and the complementary fertilization were evaluated, it was observed that the net income obtained by farmers with the increase in the hay yield (0.084 € kg−1 dry matter) over the control plots paid off the investment made in two seasons. This assay demonstrates that it is feasible to multiply hay yields in the degraded Ultisols of Spain.