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Abstract Golf courses represent an agricultural activity wherein grass is intensively cultivated using large quantities of fertilizers. In the present study, nitrogen and phosphorus leaching was analyzed over two years in an experimental green under actual field conditions. The green contained four plots with distinct amendments (P1: hydrogel + peat, P2: peat, P3: hydrogel, and P4: no amendment). The applied doses of nitrogen ranged from 5 to 103 kg/ha and of phosphorus from 9 to 31 kg/ha. The irrigation level varied as a function of the rainfall regime and the water requirements of grass; overall water intake varied from 1550 to 2080 mm/year. Daily, leached water volume was calculated, and samples were taken for chemical analysis. Nitrogen and phosphorus mass balances were calculated for different periods based on the collected data. The plot amended with peat and hydrogel (P1) had reduced water flow; the percentage of drainage water varied from 8.4 to 29%. As a result, the dissolution and leaching of nitrogen (N) and phosphorus (P) were the lowest in comparison to the other plots. According to the calculated mass balances, the lowest leaching values were also recorded in this plot (P1), ranging from 0.5 to 6.3% for N and from 0.8 to 20.9% for P. The plot without amendment (P4) drained the most water (25.9–44.8%) and leached the highest quantities of N and P, ranging from 9.1–45.7%, and 6–35.9%, respectively. The use of double amendments (hydrogel and peat) therefore represented optimal operating conditions for the green. Moreover, a relationship was found between increasing rates of fertilization and increasing percentages of N and P leaching as well as between higher irrigation levels and greater leaching. Graphical abstract Unlabelled Image Highlights • Hydrogel amendment reduces N and P leaching as well as water percolation. • Peat amendment does not impact the percentage of leached N. • The largest amount of N and P leached is detected in the plot no amendment. • A larger irrigation rate (>10 mm) favors leaching of N and P, and water percolation. [ABSTRACT FROM AUTHOR]

Depression storage (DS) is the maximum storage of precipitation and runoff in the soil surface at a given slope. The DS is determined by soil roughness that in agricultural soils is largely affected by tillage. The direct measurement of DS is not straightforward because of the natural permeability of the soil. Therefore, DS has generally been estimated from 2D/3D empirical relationships and numerical algorithms based on roughness indexes and height measurements of the soil surface, respectively. The objective of this work was to evaluate the performance of some 2D models for DS, using direct and reliable measurements of DS in an agricultural soil as reference values. The study was carried out in experimental microplots where DS was measured in six situations resulting from the combination of three types of tillage carried out parallel and perpendicular to the main slope. Those data were used as reference to evaluate four empirical models and a numerical method. Longitudinal altitudinal profiles of the relief were obtained by a laser profilometer. Infiltration measurements were carried out before and after tillage. The DS was largely affected by tillage and its direction. Highest values of DS are found on rougher surfaces mainly when macroforms cut off the dominant slope. The empirical models had a limited performance while the numerical method was the most effective, even so, with an important variability. In addition, a correct hydrological management should take into account that each type of soil tillage affects infiltration rate differently. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Two distinct slopes (resistances) are obtained in current–voltage (I–V) plots of discontinuous, conductive fiber-reinforced cement composites. The low-field resistance correlates with the DC resistance (RDC) of each composite. The high-field resistance correlates with the intermediate frequency cusp resistance (Rcusp) in Nyquist (−Zimag vs. Zreal) plots obtained using impedance spectroscopy (IS). A model is developed that is based on passive oxide film formation on copper or steel fiber surfaces at low fields (I–V) or low frequencies (IS) due to the high pH pore solution of cement paste. With increase of field, leading to film breakdown (active or transpassive corrosion behavior), or increase of frequency, leading to short-circuiting of the passive layer, the fibers act as short-circuiting elements in the composite microstructure, resulting in a decrease in overall resistance. [Copyright &y& Elsevier]

Highlights: [•] AnnAGNPS was evaluated for predicting runoff and sediment in agricultural watershed. [•] AnnAGNPS showed good ability to simulate runoff after calibration. [•] Sediment load was satisfactory predicted at annual scale but not monthly and seasonally. [•] Findings showed a suitable applicability of AnnAGNPS at annual scale. [ABSTRACT FROM AUTHOR]

Abstract: It is recognised that the hydrological and erosion processes in watersheds are very much conditioned by the (inter)action of a number of variables. This paper covers a 15-year period of studying those factors that have a major influence on the sediment yield and transport during individual hydrological events in a small Mediterranean agricultural watershed. Multivariate statistical techniques such as cluster analysis and principal component analysis were applied for the interpretation of datasets. In addition, the relationships between suspended sediment concentration and discharge (hysteretic loops) were also analysed. The hydrological response of the studied watershed is mainly controlled by the antecedent condition of the flow. Most of the runoff and sediment are generated during the wet season when vegetation cover is scant and saturation overland flow occurs promptly as a response to almost any rainfall events. In contrast, during the dry seasons even if high-intensity rainfalls normally occur, very scant runoffs are, however recorded, at the exit of the watershed. Most of the eroded sediment seems to come from riparian areas. The discharge registered at the watershed outlet up to 1h prior to the flood is a very good surrogate for antecedent soil moisture. [Copyright &y& Elsevier]

Abstract: An experimental watershed (Oskotz principal– Op –ca.1700ha) covered with forest and pasture (cattle-breeding) with an equally experimental sub-watershed (Oskotz woodland – Ow – ca. 500ha) almost entirely under forest was continuously monitored during 8 years (2001–2008). These watersheds were established by the Government of Navarre (Spain) in order to assess the impact of agricultural activities on different region of Navarre. The first results regarding exported sediment, runoff, nitrate and phosphate are presented herein. These results are compared with those from two grain-sown watersheds previously reported by the authors, elsewhere. The same as in the grain-sown watersheds, most runoff, sediment, nitrate and phosphate yields in Oskotz were generated during winter, though most erosive rainfalls occurred during summer. In Ow, average sediment, nitrate and phosphate yields were approximately: 700, 22, 0.35kghayear−1, respectively; for Op these figures were 550, 54 and 0.76kghayear−1, respectively. However, total sediment and solute yields were different depending on the prevailing land use: cereal crops>forest>pasture. Sediment yields in the forest were strongly affected by the logging moment, when exported sediment rocketed. Nitrate concentration and yields were lower (and under the critical threshold) in the forested/pastured watersheds than those recorded in the two intensively cultivated watersheds. However, phosphate yields were dramatically higher (and over the critical threshold) in the former watersheds due to the prevailing soil conditions and to the fertilization of pasture, mainly with slurry. The present work, along with that similar one recently reported by the authors, is an unprecedented and relevant piece of research for the region. [Copyright &y& Elsevier]

Abstract: Two experimental watersheds, La Tejería (1.69km2) and Latxaga (2.07km2), appointed by the Government of Navarre (Spain) for assessing the effect of agricultural activities on the environment, were monitored during 10 years (1996–2005). Both watersheds are roughly similar with regard to soils, climate (humid sub Mediterranean) and land use (almost completely cultivated with winter grain crops). The first results for both sites on runoff, exported sediment, nitrate and phosphate are presented. Most runoff, sediment, nitrate and phosphate yields were generated during winter, when variability was also the highest of the whole year. La Tejería had much higher sediment concentrations and sediment yield than Latxaga. Nitrate concentrations were also significantly higher at La Tejería, with values constantly over the critical threshold (>50mgNO3 l−1). However, phosphate concentrations were similar in both watersheds and corresponded to water with a significant risk of eutrophication. Differences in watershed behaviour could be mainly due to differences in morphology, topography, and amount of stream channel vegetation between both sites. This is an unprecedented research for the region and the generated dataset is of paramount importance for research issues such as hydrology, erosion and water quality. The results highlight the complexity of Mediterranean agricultural landscapes and the need for further analyses to better ascertain the processes behind them. [Copyright &y& Elsevier]