Long-term fertilization with dairy cattle slurry in intensive production systems: effects on soil porosity and pore morphology

In Mediterranean environments, livestock effluents might improve soil physical properties. The study was located in an intensive crop production system of northwest Spain. After nine consecutive years of dairy cattle slurry (DCS) use as fertilizer, the aim of the experiment was to evaluate the impacts of DCS on soil porosity and pore shape. Soil texture was loam. The applied DCS rates were equivalent to 170 and 250 kg N ha−1 (170DCS and 250DCS, respectively) and they were complemented with mineral N up to 450 kg N ha-1 (two crops). A nonfertilized control was included. Digital binary images were obtained from soil thin sections. Pores with an apparent diameter (AD) >30 µm were analysed. The 250DCS treatment improved soil porosity (>30 µm): it doubled in comparison with the 170DCS and the control. The application of DCS favored the presence of pores with an AD >400 µm, the roughness for AD >100 µm and the elongation in the AD interval of 100-200 µm. From the study, the 250DCS treatment is recommended as it increases macroporosity (compaction reduction) and produces more elongated and tortuous pores, which will be a constraint for fast drainage but it will be advantageous in coarse textured soils.In Mediterranean environments, livestock effluents might improve soil physical properties. The study was located in an intensive crop production system of northwest Spain. After nine consecutive years of dairy cattle slurry (DCS) use as fertilizer, the aim of the experiment was to evaluate the impacts of DCS on soil porosity and pore shape. Soil texture was loam. The applied DCS rates were equivalent to 170 and 250 kg N ha−1 (170DCS and 250DCS, respectively) and they were complemented with mineral N up to 450 kg N ha-1 (two crops). A nonfertilized control was included. Digital binary images were obtained from soil thin sections. Pores with an apparent diameter (AD) >30 µm were analysed. The 250DCS treatment improved soil porosity (>30 µm): it doubled in comparison with the 170DCS and the control. The application of DCS favored the presence of pores with an AD >400 µm, the roughness for AD >100 µm and the elongation in the AD interval of 100-200 µm. From the study, the 250DCS treatment is recommended as it increases macroporosity (compaction reduction) and produces more elongated and tortuous pores, which will be a constraint for fast drainage but it will be advantageous in coarse textured soils

Slurry field management and ammonia emissions under Mediterranean conditions

11 Pags., 2 Tabls., 2 Figs. The definitive version is available at: http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1475-2743In Spain, farmers are interested in applying pig (Sus scrofa domesticus) slurry (PS) to their fields throughout the year. During the spring and summer months, ammonia (NH3) volatilization may be high. We studied the potential range of NH3 losses under a warm and a hot period of the year, using available field practices, and two strategies: PS directly incorporated into the soil, in spring (I-spring); and PS applied by splash-plate, in summer time (SP-summer), both to bare soil. Measurements were conducted, after PS application, using the micrometeorological mass balance integrated horizontal flux method. The cumulative NH3-N volatilization was 35% (I-spring) and 60% (SP-summer) of total ammonium nitrogen applied, and half of the total NH3-N losses happened by 17 h and 8 h, respectively, after application. Incorporation strategy was less effective in avoiding NH3 losses than is described in the literature. This fact has important consequences for the implementation of NH3 mitigation measures in Mediterranean agricultural systems.This study was supported by the National Institute for Agricultural and Food Scientific Research and Technology of Spain-INIA (projects RTA2004-114 and RTA2010-126) and by FEDER (European Fund for Regional Development) and FEADER (European Agricultural Fund for Rural Development) funds.Peer reviewe

Measurement and estimation of the fertiliser value of pig slurry by physicochemical models: Usefulness and constraints

38 Pags., 4 Figs., 5 Tabls. The definitive version is available at: http://www.sciencedirect.com/science/journal/15375110Pig slurries (PS) are widely applied to soil as fertilisers. Compositional variability, as shown in this study, is the main constraint on their efficient use. Slurry samples, collected from 126 commercial pig farms were analysed and organic nitrogen (ON), ammoniacal nitrogen (AN), total nitrogen (TN), total potassium (TK), total phosphorus (TP) content, pH, EC (electrical conductivity), DM (dry matter) and OM (organic matter) quantified. Relationships between major nutrient contents of PS and its physical and chemical properties were analysed. AN and TK were linearly related to EC (p 40 dS m−1) linearity cannot be maintained, which has important consequences for direct slurry EC measurements. ON and TP in slurries were closely related (p < 0.0001) to DM with R2 of 0.90 and 0.68 respectively.This study was funded by the National Institute for Agricultural and Food Scientific Research and Technology of Spain (INIA), projects SC00-061, RTA04-114 and RTA10-126.Peer reviewe

Ammonia emissions from different fertilizing strategies in Mediterranean rainfed winter cereals

32 Pags., 4 Tabls., 3 Figs. The definitive version is available at: http://www.sciencedirect.com/science/journal/13522310Anthropogenic ammonia (NH3) emissions mainly result from agricultural activities where manure spreading plays a significant role. For a Mediterranean rainfed winter cereal system there is a lack of data regarding NH3 emissions. The aim of this work is to provide field data on N losses due to NH3 volatilization as a consequence of the introduction of slurries in fertilization strategies and also, to assess the influence of environmental conditions and slurry characteristics on emissions. The fertilizing strategies include the use of slurry from fattening pigs (PS), sows (PSS) and/or mineral fertilizer (M) as ammonium nitrate. Fertilizers were spread over the calcareous soil at sowing and/or at tillering at rates from 15 to 45 kg NH4+–N ha−1 for M and from 48.8 to 250.3 kg NH4+–N ha−1 for slurries. The NH3 emissions were quantified during three cropping seasons. Average losses from the total ammonium nitrogen applied ranged from 7 to 78% for M and from 6 to 64% for slurries and they were not directly proportional to the amounts of applied ammonium. The best results on NH3 volatilization reduction were registered when soil water content (SWC, 0–30 cm) was below 56% of its field capacity and also, when slurry dry matter (DM) was in the interval of 6.1–9.3% for PS or much lower (0.8%) for PSS. High slurry DM favoured crust formation and the lower rates promoted infiltration, both of which reduced NH3 emissions. Nevertheless, at tillering, the lower DM content was the most effective in controlling emissions ( 0.05). A single slurry application at tillering did not negatively affect yield biomass. The combining of recommended timing of applications with slurry DM content and SWC should allow producers to minimize volatilization while maintaining financial benefits.This study was financed by the National Institute for Agricultural and Food Scientific Research and Technology of Spain-INIA (projects: REN01-1590, RTA04-114, RTA2010-126) and by FEDER (European Fund for Regional Development) and FEADER (European Agricultural Fund for Rural Development) funds.Peer reviewe

Structural changes in humic substances after long- term fertilization of a calcareous soil with pig slurries

Pig slurries are widely used on calcareous soils in European rainfed systems. Here we assess their impact on the amount of soil organic carbon (SOC) and on the composition of humic- type substances (HTS). Seven doses of slurry (five from fattening pigs and two from sows) ranging from 1.0 to 4.8 Mg ha−1 yr−1 of or-ganic matter were evaluated after a period of 12 years and compared with mineral fertilizer treatment. At the end of the last annual cropping season (September), SOC was quantified, and HTS were isolated by alkaline extraction followed by acid precipitation, and studied by visible spectroscopy (800– 400 nm) and Fourier- transformed infrared spectroscopy (4000– 400 cm−1). Following the trend in the slurry organic matter applied rates, SOC increased from 9.5 g C kg−1 (min-eral treatment) to 13.8 g C kg−1. This SOC increase was equivalent to c. 25.4% of the slurry organic carbon applied. The incorporation of aliphatic structures, mainly polyalkyl, from slurries into the HTS tends to modify the composition of the soil organic matter (SOM), which is reflected in a decrease in the intensity of FT- IR peaks related to aromatic structures. Despite the trend of significant increase in SOC with fattening slurries, mainly from the organic matter rate of 1.6 Mg ha−1 yr−1 (c. 185 kg N ha−1), the composition of the HTS showed an impor-tant aliphatic enhancement. The FTIR results showed that using exclusively the relative intensities of specific peaks (alkyl, carboxyl, aromatic and amide groups) as variables for the discriminant analysis, it is possible to identify HA between different groups of soils treated with progressive levels of slurry. Although the new aliphatic components could be considered important to improve soil physi-cal quality, after the incorporation of additional SOM, the spectroscopic charac-teristics of HTS in soils treated with slurries suggested a weak effect in long- term C sequestration, as the newly incorporated OC forms are not qualitatively similar to the presumably stable native SOM. These potential changes in SOC and SOM composition at field level are constrained by the maximum allowed N rates from organic origin in some agricultural systems.This research was supported by the Spanish Ministry of Science, Innovation and Universities and the Spanish National Institute for Agronomic Research (MICINN- INIA) through the project RTA2017- 88- C3- 3. D.E. Jiménez- de- Santiago also acknowledges the JADE- Plus scholarship from Bank of Santander- University of Lleida for her PhD studies.Peer reviewe