Abstract. When soil nitrate levels are low, plants suffer ni- trogen (N) deficiency but when the levels are excessive, soil nitrates can pollute surface and subsurface waters. Strategies to reduce the nitrate pollution are necessary to reach a sus- tainable use of resources such as soil, water and plant. Buffer strips and cover crops can contribute to the management of soil nitrates, but little is known of their effectiveness in semi- arid vineyards plantations. The research was carried out in the south coast of Sicily (Italy) to evaluate nitrate trends in a vineyard managed both conventionally and using two differ- ent cover crops (Triticum durum and Vicia sativa cover crop). A 10 m-wide buffer strip was seeded with Lolium perenne at the bottom of the vineyard. Soil nitrate was measured monthly and nitrate movement was monitored by applica- tion of a 15 N tracer to a narrow strip between the bottom of vineyard and the buffer and non-buffer strips. Lolium perenne biomass yield in the buffer strips and its isotopic nitrogen content were monitored. Vicia sativa cover crop management contributed with an excess of nitrogen, and the soil manage- ment determined the nitrogen content at the buffer areas. A 6 m buffer strip reduced the nitrate by 42 % with and by 46 % with a 9 m buffer strip. Thanks to catch crops, farmers can manage the N content and its distribution into the soil over the year, can reduced fertilizer wastage and reduce N pollu- tion of surface and groundwater.
An automated combustion elemental analyzer in- terfaced with an IRMS (ANCA-SL system) was used to measure total nitrogen content as well as the ni- trogen isotopic composition of soil samples (14 ± 0.1 mg). Samples were prepared as described in Schepers et al. (1989). Sharpsburg silty clay loam (δ 15 N = 10.647) was used as the soil work- ing standard. Overall precision (machine error plus sample preparation error) for nitrogen isotopic com- position was 0.3–1.
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The results demonstrate advantages of farmyard ma- nure and legume crops, which apparently supply to the soil more stabilized components with slow mineralization that will renew or increase soil productivity. As stated by Kubát et al. (1999), nitrogen cannot be accumulated in soils in other than organic form. Therefore mineral ni- trogen must be consumed by plants or by microorgan- isms; otherwise there is a risk of its losses. From this aspect, the most efficient measure for the environment conservation is adequate crop production and creation of conditions for the formation of stable organic compo- nents in soil.
At present, the majority of agronomists believe that optimizing conventional intensive agriculture could lead to a reduction in resource consumption and the associated environmental pollution while maintaining high grain yield (Tilman et al. 2002, Galloway et al. 2008, Mueller et al. 2012). Studies conducted in the NCP have shown that N input reductions of 30–60% can be achieved through optimization of N management alone, without sacrificing grain yield (Ju et al. 2009). The results showed that the two optimized cropping systems reduced N fertilizer input, water consumption and NO 3 – -N leaching by 33, 35 and 67–74%, respec- tively, compared to the conventional cropping system, while also generating nearly identical grain yields (Tables 2–4). In the optimized systems, soil NO 3 – -N accumulation within the root zone was 0
soil profile below the top foot (Spellman et al. 1996), leaching losses with irriga- tion water (Magdoff 1991) or low N min- eralization potentials of the soils. This variability suggests that in areas with erratic and low winter rainfall, a PSNT threshold value is unlikely to reliably predict whether a sidedress application is needed by irrigated crops that are sid- edressed only toward the beginning of a long season. In summary, PSNT thresh- olds developed for field crops in humid regions, which assume a consistent re- lationship between NO 3 − -N present in
DNRA and denitriﬁcation. 15 N isotope labeling techniques pro- vides a means for identifying the active soil process and has been used at small scales in freshwater sediment by Stief et al. (2010). They were able to quantify NH + 4 production by DNRA at a res- olution of 1–2.5 mm. This was achieved by adding 15 N labeled NO − 3 to sediment and quantifying 15 NH + 4 that had been trapped on a polyacrylamide gel inserted into the sediment. Care must be taken when sampling small areas as the act of placing sensors or gels into the soil will alter the soil structure and hence the small scale variability in conditions that are needed to link com- munity and ﬂux. Factors such as bulk density, nutrient ﬂow, gas diffusion, and community composition may all be altered by the disruption of soil structure. As with any small scale measure of soil variability there will be problems with identifying the exact point in soil that is being measured, as it will need to be identi- ﬁed through an opaque medium. Methods of imaging soil such as X-ray CT scanning, described above, may provide a solution for this but this can only derive the physical structure of the matrix and cannot resolve the processes or associated microbial communities.
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Abstract. Lack of real-time information on nutrient avail- ability in cultivated soils inherently leads to excess applica- tion of fertilizers in agriculture. As a result, nitrate, which is a soluble, stable, and mobile component of fertilizers, leaches below the root zone through the unsaturated zone and even- tually pollutes the groundwater and other related water re- sources. Rising nitrate concentration in aquifers is recog- nized as a worldwide environmental problem that contributes to water scarcity. The development of technologies for con- tinuous in situ measurement of nitrate concentration in soils is essential for optimizing fertilizer application and prevent- ing water resource pollution by nitrate. Here we present a conceptual approach for a monitoring system that enables in situ and continuous measurement of nitrate concentration in soil. The monitoring system is based on absorbance spec- troscopy techniques for direct determination of nitrate con- centration in soil porewater without pretreatment, such as filtration, dilution, or reagent supplementation. A new an- alytical procedure was developed to improve measurement accuracy while eliminating the typical measurement inter- ference caused by soil dissolved organic carbon. The ana- lytical procedure was tested at four field sites over 2 years and proved to be an effective tool for nitrate analysis when directly applied on untreated soil solution samples. A soil nitrate-monitoring apparatus, combining specially designed optical flow cells with soil porewater-sampling units, en- abled, for the first time, real-time continuous measurement of nitrate concentration in soils. Real-time, high-resolution measurement of nitrate concentration in the soil has revealed the complex variations in soil nitrate concentrations in re- sponse to fertigation pattern. Such data are crucial for opti-
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Abstract. Highly productive sown pasture systems can result in high growth rates of beef cattle and lead to increases in soil nitrogen and the production of subsequent crops. The nitrogen dynamics and growth of grain sorghum following grazed annual legume leys or a grass pasture were investigated in a no-till system in the South Burnett district of Queensland. Two years of the tropical legumes Macrotyloma daltonii and Vigna trilobata (both self regenerating annual legumes) and Lablab purpureus (a resown annual legume) resulted in soil nitrate N (0–0.9 m depth), at sorghum sowing, ranging from 35 to 86 kg/ha compared with 4 kg/ha after pure grass pastures. Average grain sorghum production in the 4 cropping seasons following the grazed legume leys ranged from 2651 to 4012 kg/ha. Following the grass pasture, grain sorghum production in the ﬁrst and second year was <1900 kg/ha and by the third year grain yield was comparable to the legume systems. Simulation studies utilising the farming systems model APSIM indicated that the soil N and water dynamics following 2-year ley phases could be closely represented over 4 years and the prediction of sorghum growth during this time was reasonable. In simulated unfertilised sorghum crops grown from 1954 to 2004, grain yield did not exceed 1500 kg/ha in 50% of seasons following a grass pasture, while following 2-year legume leys, grain exceeded 3000 kg/ha in 80% of seasons. It was concluded that mixed farming systems that utilise short term legume-based pastures for beef production in rotation with crop production enterprises can be highly productive.
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At the physiological maturity stage, the soil ni- trate content in each layer was decreased signifi- cantly than those of the early stages both in 2006 and 2007 (Figure 4). Without irrigation, the soil nitrate content of CU was lower than NU at the same level of nitrogen used. But with irrigation at the blister stage, the soil nitrate content of C2 in 30–40 cm soil layers were higher than those of N2, which can be used by following crops. When urea type was the same, the soil nitrate content could be increased with the increment of nitrogen fertilizer used. When only normal urea was used, the soil nitrate content could be increased with increased nitrogen supplied (Fang et al. 2006). The soil nitrate content with irrigation was higher than that without irrigation, and the soil nitrate content of CU was lower than that of NU. Leaching of nitrate may be the main reason of soil nitrate decrease. Compared with NU, CU can increase the yield of maize (Shoji et al. 1991), which resulted in its ‘early-decrease-and-late increase (EDLI)’ effect, that is, the growth of CU was lower at the 14 th leaf stage, but significantly higher after the
Studies were performed to determine the loss of soluble forms of organic carbon in differently used meadows on mineral soil. In a long-term experiment two variants were distinguished: a productive meadow (N120-AN and N120-CN) and a non-productive one (Kp-AN, Kp-CN, Kz-AN, Kz-CN). Productive meadows were fertilized with 120 kg N/ha/year, 34.9 kg P/ha/year, and 149.4 kg K/ha/year and mown three times a year. Nitrogen fertilization was applied in a form of ammonium nitrate (AN) and calcium nitrate (CN). The only agro-technical measure applied to non-productive meadows was the regular cutting of vegetation and leaving it on the plots (variants: Kp-AN and Kp-CN) or taking it away from the plots (variants: Kz-AN, Kz-CN). Significant positive Pearson’s linear correlations were found between pH (in CaCl 2 ) of mineral soil and total organic carbon (TOC) content in the following variants: Kz-AN (r = 0.457**), N120-AN (r = 0.491**), and N120-CN (r = 0.424**) and in all meadows fertilized with AN (r = 0.243**). The obtained linear correlation coefficients between pH and TOC indicate that soil organic carbon may be lost as a result of progressive acidification of the soil. Dissolved organic carbon in the mineral meadow soil increased in the following order: Kp-CN > N120-CN > Kz-CN > N120-AN > Kp-AN > Kz-AN. Keywords: dissolved organic carbon; meadow experiment; mineral soil; total organic carbon
Soil temperature was monitored insitu at the site of collection of samples using mercury-in-glass thermometer while soil pH was determined using pH meter as described by Bates (1954). Soil moisture was measured using method of APHA (1998). However, soil samples exchangeable acidity, cation exchange capacity. sulphate, phosphate, and nitrate were determined using the methods of Dewis and Freitas (1970). Soil sample ammonium ion was measured using the method of Vogel (1962) while sodium, potassium and aluminium ions in soil samples were determined using Atomic Absorption spectroscopy according to AOAC (2005). All statistical analyses were done using ANOVA and Duncan Multiple Range.
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The assumption of an exponential decrease in root length density with depth has been adopted in several models, with a fixed low root density at the calculated rooting depth, but a varying form factor to distribute increased root length mainly with increasing root density in the uppermost soil layers (Abrahamsen and Hansen, 2000; Barraclough and Leigh, 1984; Greenwood et al., 1982). This exponential decrease has been shown to match monocots such as grasses and cereals reasonably well and was demonstrated here also for the vegetable crop leek, but not for dicot species such as oil radish or winter rape (Thorup-Kristensen, 2001). In the model presented here, it was possible to vary the root length density distribution among soil layers, and to increase root length density in deeper soil layers using a fixed value of the form parameter but allowing root density to vary at calculated rooting depth. This variation in root distribution provides the opportunity to simulate a range of different crop species with significantly different root
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Abstract: The effect of fertilization with a new fertilizer on Polish market, a mixture of ammonium nitrate and am- monium sulfate (30% N, 6% S), was analysed in a three-year field experiment. The mixture commonly available on the market (26% N, 13% S) and ammonium nitrate, were used for comparison. Each fertilizer was applied in three doses: 150, 200 and 250 kg N/ha/year (simultaneously, 30, 40 and 50 kg S/ha were introduced with the mixtures). The highest mean (of the three years) grain yield (8.27 t/ha) was obtained after application of 200 kg N and 40 kg S/ha as the new fertilizer, with almost no significant effect of the type and dose of sulfur-containing fertilizers. Sulfur content in the grain was highest after the new fertilizer application; the content increased with increasing fertilizer dose. The highest mean protein (13.9–14.3%) and gluten (28.3–28.9%) content were recorded after application of 250 kg N/ha, and Zeleny sedimentation index (45.0–45.3 cm 3 ) – after application of 250 kg N and 50 kg S/ha, regardless of the
nitrogen concentration in the top 30 cm of the soil profile and directly under the drip emitter was initially 400 to 550 mg/L (Figure 3-10). At a distance of 15 cm from the drip emitter the concentration was only slightly lower with a concentration range of 300 to 500 mg/L (Figure 3-10). As the season progressed these values were observed to decrease significantly and most notably at a greater rate after the switch from sprinkler to drip irrigation. The reduction was observed to follow a period of rainfall and no fertiliser application (Figure 3-8). The soil solution data (Figure 3-10) and soil moisture data (Figure 3-9) showing movement of water at depth suggests that the presence of in- season rainfall was a significant cause of nitrate movement through the profile. However, it should be noted that at depths and distances away from the drip emitter wetted zone, the nitrate concentrations remained persistently high. This suggests that this area may have been drier prior to the rainfall events and likely suffered less drainage and nitrate loss. This confirms that the nitrate movement within the soil profile is highly dependent on water movement.
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DOI: 10.4236/ojss.2019.94004 67 Open Journal of Soil Science density for container culture of radish seedlings. Urea (46% N) was added at a rate of 1.25 g per 5” container containing 1.54 kg of blended sand and site soil to provide nitrogen for seedling growth. Five varieties of radish and one of mustard were obtained from High Mowing Organic Seeds (Wolcott, VT, USA) and seeded 1gm of each variety in each experimental unit (container). The study in- cluded radish cultivars “Cherry Belle”, “White Beauty”, “Purple Plum”, “French Breakfast” and “Rudolf” as well as the known lead hyper-accumulator Red Giant Mustard (RGM) Brassica juncea L. As a control, one of the radish cultivars (“White Beauty”) and RGM were grown in soil-less media composed of peat moss and sand (50:50 vol:vol) and fertilized with urea as above.
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Samples used in this investigation originate from col- lection Minning-geological Faculty. Loess originates from the location of Bezanija, while sand originates from the short of Sava River. First, the aim was to determine minerals presented in mentioned samples. On the sand sample it was conducted recording of complete cut up in small pieces dust, whilst at samples of loess after re- corded complete sample, there was determined the pres- ence of mineral of clay. Then we are present to extracting fraction of clay, preparing samples on glass tile and re- cording with additional treatment, in order to confirm presence of certain minerals of clay. For recording was used x-ray aparatus Philips 1010, and we have conducted x-ray difraction analysis referently oriented preparation of clay. Sample of clay was then exposed to etilenglicol vapor for 24 hours, and then the sample was heating to red on 550˚C for 30 min, and all was again recorded. Because in this paper , beside economic and ecological aspect, it was justifed that, in order to perceive impact of implementation of mineral fertilizers on underneath wa- ter and soil, we do also and additional analasies that will
To extract sulphate, 5.0 mL of magnesium nitrate solutions were added to each of the ground and sieved samples in the crucibles. These were then heated to 180 °C on a hot plate (Huart SB162). The heating process was allowed to continue until the colour of the samples changed from brown to yellow (Helrich, 1990). The samples were then transferred to the furnace at a temperature of 500 °C for four hours. Magnesium nitrate was added to prevent loss of sulphur. The contents of each crucible were carefully transferred to different evaporating basins. A 10.0 mL portion of concentrated HCl was added to each of them and covered with watch glasses. They were boiled on a steam bath for 3 minutes. On cooling, 10.0 mL of distilled water were added to each of the basins and the contents of each were filtered into 50.0 mL volumetric flasks and the volumes made up to the marks with distilled water (Radojevic and Bashkin, 1999). Sulphate was determined using turbidmetric method (Massuomi and cornfield, 1963).
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Catch crops are often sug- gested as a measure to re- duce nitrate leaching. In the maize experiment leaching tended to be less (12 kg N/ ha) in unfertilized maize when a perennial ryegrass catch crop was included rather than leaving the soil bare after harvest (Table 1). In fertilized maize, leaching also tended to be less (21 kg N/ha) with a catch crop, but the difference between the two fertilized treatments with or without a catch crop was not significant.
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trients from wastewater, and then the loaded biochar or mixture of sludge and biochar could be added to soil. Digestate from anaerobic digestion of sewage sludge, manure and residues from the food/beverage or agricul- tural industry usually contains high levels of nutrients which makes it suitable for utilization as an organic soil fertilizer . Using biochar to extract and concentrate the nutrients could eliminate current difficulties asso- ciated with the storage of high volumes of the digestate and other waste liquids, and also eliminate environmen- tal concerns relating to spreading the high volumes of liquid fertilizer on soil. In some wastewaters, adsorption of heavy metals and other harmful substances in addition to nutrient could be a problem, but in the case of farm waste or residues from the food beverage industry it should be safe.
compared to two other seasons while during the second year (2010-11) the nitrate content was lower in summer and higher in rainy compared to two other seasons (Table1 to 3; Fig. No. 1 to 7). Nitrate is a problem as a contaminant in surface water and (primarily from groundwater and wells) due to its harmful biological effects. High concentrations can cause methemoglobinemia, and have been cited as a risk factor in developing gastric intestinal cancer (Pondhe, 2005).
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