Fernando Peregrina

Cover crops and tillage influence soil organic matter and nitrogen availability in a semi-arid vineyard

Little attention has been given to the utilization of permanent cover crops in vineyard agroecosystems in semi-arid Mediterranean climatic conditions to increase soil organic carbon or its effects on N availability. We evaluated the effect of permanent cover crops with resident vegetation on labile organic matter fractions and inorganic N availability with respect to conventional tillage in a semi-arid vineyard. The field experiment was conducted on Typic Haploxerept soil, located in La Rioja area (Central River Ebro Valley). Soil samples were collected during June 2009, 5 years after covers crops were established. Soil organic carbon (SOC), water-soluble carbon (WSC), potentially mineralizable nitrogen (PMN), nitrate (N-NO3 −) and ammonium (N-NH4 +) were measured. At soil depths of 0–2.5 and 2.5–5 cm the cover crops increased SOC, WSC and PMN. So the results indicated a soil quality improvement. The cover crop treatment reduced soil N-NO3 − and increased the WSC to inorganic N ratio at 0–45 cm depth. PMN and WSC increments suggest a more active microbial biomass that could promote the immobilization and recycling of N-NO3 −, and therefore might partially explain the reduction in N-NO3 − pools under cover crops.

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.

Soil nutrient availability under Cover Crops: Effects on vines, must, and wine in a Tempranillo Vineyard

Cover crops can compete with vines for soil nutrients and thus can affect grapevine development and must and wine quality. The objective of this study was to evaluate the influence of two different cover crops on the availability of soil N, P, K, and Mg and on grapevine nutritional status, vigor, yield, and must and wine quality. The experiment was carried out in a cv. Tempranillo vineyard in La Rioja, Spain, using three treatments: a gramineous cover crop (barley), a leguminous cover crop (clover), and conventional tillage. Soil nitrate evolution and P, K, and Mg were determined, and total biomass and nutrient content of cover crops were measured. We also assessed leaf nutrient content, vine vigor, yield, and must and wine quality. Uptake of P, K, and Mg by cover crops did not reduce the soil availability of those nutrients and did not affect their concentrations in grapevines. The barley cover crop reduced soil N availability from the first year onward and led to decreased leaf N and vine vigor in the third year. Increased polyphenol content and color intensity were observed in the barley treatment in the fourth year, and these changes were more significant in must than in wine. The clover treatment increased soil N availability in years 2 through 4 and led to increased leaf N content in the third and fourth years. The use of barley as a cover crop could be a viable alternative for reducing soil N and improving must and wine quality; however, these effects required time to develop after introduction of the cover crop.

Cover Crop Short-Term Effects on Soil NO3 --N Availability, Nitrogen Nutritional Status, Yield, and Must Quality in a Calcareous Vineyard of the AOC Rioja, Spain

Cover crop use in vineyards can affect both vine vigor and must and wine quality because of the competition for soil nutrients and water. Our objective was to study the short-term effects of a cover crop on the nitrate (NO3 −)–nitrogen (N) availability throughout the grapevine vegetative cycle, the grapevine and cover crop N uptake, and the yield and must quality. By short-term effects we mean the first crop cycle after planting the cover crop. The experiment was set in 2009 on a cv. Tempranillo vineyard planted in a Oxyaquic Xerorthent soil. The soil had not been fertilized with N since 2000, and two types of soil management were studied: (1) conventional tillage (CT) and (2) barley (Hordeum vulgare L.) cover crop (B). Soil samples were taken in March (bud break), June (bloom), July (setting), and August (veraison) of 2009, and the extractable NO3 −-N was determined. At bloom and veraison, N contents in both blade and petiole were determined. At bloom the grapevine N uptake was estimated using the aerial parts (leaves, shoots, and bunches), and for the cover crop N uptake was determined. Total yield, bunch, and shoot weight as well as must anthocyanin and polyphenol contents were determined. Soil NO3 −-N availability decreased in the cover crop from June until August, with the reduction being similar to the cover crop N uptake. Also N contents in both petiole and blade decreased in the cover crop at veraison. Regarding must quality, the cover crop increased the anthocyanin content. The reduction of soil NO3 −-N availability throughout the vegetative cycle of grapevine caused a reduction in both N nutritional status and grapevine vigor, and therefore cover crops could affect must quality in the first harvest after the cover crop was sown.

Aluminum, Fluorine, And Sulfate Species Dynamics In The Soil Solution Of A Palexerult Amended With Lime And Gypsum By-products

Changes in the activities of aluminum (Al), fluorine (F), and sulfate (SO42−) species in the soil solution of a plinthic Palexerult after amendment with various lime and gypsum by-products [viz. sugar foam waste (SF), phosphogypsum (PG), and red gypsum (RG)] were studied in successive extracts of the soil solution from the Ap and AB horizons, which were placed in leaching columns, over two leaching cycles equivalent to two precipitation cycles in the soils originating area. Although SF affected mainly the Ap horizon, the gypsum amendment effects were more complex. Thus, SF decreased the activity of Al3+ and Al(OH)2+ in the soil solution from the Ap horizon. In contrast, SF affected the AB horizon, where it reduced the activity of Al3+ and significantly increased that of Al(OH)2+-only by the end of the second leaching cycle, however. Similar to SF, PG was found to affect the activities of Al3+, Al(OH)2+, and Al(OH)2+ species (particularly the first) in the soil solution from Ap; this by-product increased the activity of AlFx(3−x) ion pairs but not that of Al-SO4 pairs. On the other hand, RG significantly increased the activity of Al3+ in the first water extract from Ap and AB and also that of the AlSO4+ pair in the first four water extracts but only that of AlF2+ among Al-F pairs. The two gypsum amendments had similar effects on the AB horizon. Thus, they increased the activity of AlSO4+ and Al(SO4)2−, which peaked in the second soil-water extraction, and that of AlFx(3−x) pairs. Sugar foam waste significantly increased the Ca-Al balance in the Ap horizon, as did PG, albeit only in the first three soil-water extracts. The gypsum amendments also increased Ca-Al balance in AB, and so did SF after the second soil-water extract.

SOIL SOLUTION DYNAMICS INTO PALEXERULT AMENDED WITH GYPSUM AND LIME BY-PRODUCTS: A LABORATORY TEST

A laboratory experiment involving the use of leaching columns reproducing the topmost part of a clayey-skeletal kaolinitic acid thermic plinthic Palexerult amended with lime and gypsum by-products was used to study changes in soil solution composition during two leaching cycles. The lime amendment mainly affected the composition of the soil solution of the Ap horizon, where it increased pH and Ca and decreased the F and Al concentrations. Gypsum by-products caused an initial pH decrease in the soil solution; however, as the gypsum was leached, the pH rose and eventually exceeded that of both Ap and AB in the controls. After the gypsum by-product application, Mg and Na strongly increased, but afterward decreased to levels lower than those in the controls; Al contents increased in the first water extracts from Ap and AB horizons and that of F in all extracts from Ap and most from AB. The variation of the Ca and SO42− concentrations in the AB horizon was influenced by surface sorption and precipitation.

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.

Surface Soil Properties Influence Carbon Oxide Pulses After Precipitation Events in a Semiarid Vineyard Under Conventional Tillage and Cover Crops

Abstract In semiarid regions of the Mediterranean basin, a rainfall event can induce a respiratory pulse that releases a large amount of soil carbon dioxide (CO 2 ) into the atmosphere; this pulse can significantly contribute to the annual ecosystem carbon (C) balance. The impacts of conventional tillage and two different cover crops, resident vegetation and Bromus catharticus L., on soil CO 2 efflux were evaluated in a Vitis vinifera L. vineyard in La Rioja, Spain. Soil CO 2 efflux, gravimetric water content, and temperature were monitored at a depth of 0–5 cm after rainfall precipitation events approximately every 10 d in the period from May 17 to July 27, 2012, during which the cover crops had withered. Additionally, on June 10, 2012, soil organic C, microbial biomass C, and β-glucosidase activity were determined at soil depths of 0–2.5, 2.5–5, 5–15, and 15–25 cm. The results show that pulses of soil CO 2 were related to the increase in soil water content following precipitation events. Compared to the conventional tillage treatment, both cover crop treatments had higher soil CO 2 efflux after precipitation events. Both cover crop treatments had higher soil organic C, microbial biomass C, and β-glucosidase activity at the soil surface (0–2.5 cm) than the conventional tillage treatment. Each pulse of CO 2 was related to the surface soil properties. Thus, this study suggests that the enhancement of soil organic C and microbiological properties at the soil surface under cover crops may increase soil CO 2 efflux relative to conventional tillage immediately after precipitation events during the dry season.

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.

Agronomic Implications of the Application of Lime plus Gypsum By‐products to a Hyperdistric Acrisol from Western Spain

Abstract: A laboratory experiment involving the use of leaching columns reproducing the topmost portion of a Hyperdystric Acrisol (FAO 1998) or plinthic Palexerult (Soil Survey Staff 2003) treated in its Ap horizon with sugar foam wastes and phosphogypsum was conducted. The amendments increased the contents in exchangeable calcium (Ca) of the Ap horizon and, to a lesser extent, also that of the AB horizon. However, the contents in exchangeable magnesium (Mg) and sodium (Na) decreased as much in Ap as they did in AB; by contrast, the potassium (K) content exhibited a less marked decrease. The potassium chloride (KCl)–extractable aluminium (Al) of the Ap horizon was dramatically decreased much more than that of the AB horizon by the amendments. In the soil solution from Ap, the amendments raised the pH and decreased the Al concentration; in that from AB, however, they caused an initial pH decrease, a tendency that reversed as the gypsum was leached and eventually led to the pH exceeding that in the soil solution from control. The first few water extractions exhibited increased Mg concentration. This trend was reversed in the second leaching cycle, where the concentrations of Mg in the amended columns were lower than those in the controls. In the soil solution, the variation of the Ca and sulphate (SO4 2–) concentrations was influenced by the salt‐sorption effect. The total Al content in soil solution from AB increased during the first leaching cycle and then decreased during the second. The amendments decreased the activities of Al3+, AlOH+2, and Al(OH)2 + in the Ap horizon and increased those of Al3+, AlSO4 +, Al(SO4)2 −, and AlF+2 in the first leaching cycle in the AB horizon. The productivity of the Ap horizon after the treatments was assessed using a wheat crop (T. aestivum, var. ‘Jabato’) in a greenhouse.