Leaching Of Mineral Nitrogen Research Articles

Effects of Different Tillage and Fertilization Methods on the Yield and Nitrogen Leaching of Fragrant Rice

Conservation tillage and deep-side fertilization both hold the potential to reduce nitrogen leaching and improve grain yield and nitrogen use efficiency in fragrant rice cultivation practices. However, the combined impact of different tillage practices with deep-side fertilization on nitrogen leaching remains uncertain. Therefore, this study conducted on-site experiments for four rice-growing seasons in both early and late seasons in 2018 and 2019 using the fragrant rice varieties “Meixiangzhan 2” (MX) and “Xiangyaxiangzhan” (XY). The four experimental treatments included the following: conventional tillage with regular fertilization (T1), conventional tillage with simultaneous deep fertilization (T2), reduced tillage with simultaneous deep fertilization (T3), and no-tillage with simultaneous deep fertilization (T4). Our results indicate that the T4 treatment exhibited higher nitrogen leaching rates and potential nitrogen losses throughout the entire rice growth cycle, with a 4.51% increase in total mineral nitrogen leaching (TMNL) and a 1.86% increase in potential nitrogen leaching compared to T1 treatment. In contrast, the T2 treatment demonstrated the lowest nitrogen leaching rate, resulting in a 6.01% reduction in TMNL and a 9.57% decrease in potential nitrogen leaching compared to T1, demonstrating the most optimal performance. It is important to note that a reduction in nitrogen leaching does not directly translate into an increase in rice yield. Our study involved the cultivation of two fragrant rice varieties, ‘Meixiangzhan2’ (MX) and ‘Xiangyaxiangzhan’ (XY), and the results revealed some interesting insights. For MX, the T1 treatment resulted in lower daily grain outputs compared to the other treatments, with disparities ranging from 5.35% to 9.94%. Similarly, for XY, the T1 treatment yielded significantly lower daily grain outputs compared to the other treatments, with discrepancies ranging from 6.26% to 10.81% during the late season of 2019. Therefore, this study suggests that conventional tillage combined with deep fertilizer application can be considered as an effective agricultural strategy to reduce nitrogen leaching and enhance fragrant rice yields.

Balancing grain yield and environmental performance by optimizing planting patterns of rice-wheat cropping systems

To alleviate the adverse consequences of conventional planting of the rice–wheat cropping system and achieve long-term sustainability, a 3-cycle experiment (2019–2022) was conducted to investigate the effects of six planting patterns (PPs) on the grain yield and environmental performance. PP1 entailed annual rotary tillage (RT) without straw returning but without fertilization for rice and wheat seasons. PP2 was the same as PP1 but involved fertilization. PP3 was the same as PP2 but included straw return. PP4 entailed rice planting the same as in PP3, but with innovative zero-tillage (ZT) seeding technology for wheat planting. PP5 entailed wheat planting the same as in PP4, but with rice planting involving direct paddy seeding under RT. PP6 entailed wheat planting the same as in PP4, but rice planting followed dry direct seeding under ZT. The results showed that the average total yield under PP2, PP3, PP4, PP5, and PP6 was 64 %, 54 %, 69 %, 51 %, and 54 % higher than that under PP1, respectively. The highest methane and nitrous oxide emissions occurred under PP4 and PP6, respectively. When soil organic carbon changes were included in the calculations, the carbon footprint per unit area (CFA) was sharply reduced under PP4 and PP6, and the highest CFA was achieved under PP1, followed by PP2. Implementing annual RT promoted soil mineral nitrogen accumulation under PP2 and PP3 after wheat harvest, increasing the risk of mineral nitrogen leaching and the nitrogen footprint per unit area than that under the other PPs. PP4 exhibited the highest ammonia volatilization, which was offset by reduced mineral nitrogen leaching. Overall, PP4 exhibited a yearly increase in the comprehensive scores obtained via Z-score analysis and yielded the highest score in the last year due to the highest annual grain yield, steady SOC increase, and lower nitrogen loss.

Quantifying the impact of induced topsoil and historical subsoil compaction as well as the persistence of subsoiling

Mechanical soil compaction increasingly occurs in arable land but the state and effects of historical compaction from regular operations are still poorly documented. Therefore, a typical field was selected and the effects of both newly formed topsoil compaction and historical developed subsoil compaction (below 30 cm) on soil physical and hydraulic properties, soil water movement, soil mineral nitrogen leaching potential and crop parameters were evaluated on a Luvisol under a winter rye (Secale cereale L.) and summer maize (Zea mays L.) rotation system. Three subsoil compaction levels were included, i.e., a i) highly compacted headland zone, and a moderately compacted in-field zone ii) without and iii) with deep tillage by subsoiling in the winter of 2016. Topsoil compaction on the other hand was induced by one machine pass with a rotary cultivator in addition to the regular machine passes during field preparation for the summer maize season of 2017, and compared with a control without extra compaction. For subsoil compaction treatments, both visual evaluation and lab or field based measurements indicated that soil physical and hydraulic properties were deteriorated in the headland compared with in-field zones. As a result, both winter and summer crop above-ground biomass were decreased in the highly compacted headland zone because of the restricted root growth, which further increased the risk of soil mineral nitrogen leaching. The alleviation effect of deep tillage remained after ∼ 2 years, which significantly increased maize height in the extremely dry and hot summer of 2018. For topsoil compaction, one traffic pass with a rotary cultivator increased topsoil penetration resistance and water content but summer maize above-ground biomass was not affected. Overall, prevention and alleviation of subsoil compaction are essential in increasing the resistance and resilience to the continuing deteriorating climatic conditions.

Optimizing nitrogen management reduces mineral nitrogen leaching loss mainly by decreasing water leakage in vegetable fields under plastic-shed greenhouse

Excessive fertilization leads to high nitrogen (N) leaching under intensive plastic-shed vegetable production systems, and thereby results in the contaminations of ground or surface water. Therefore, it is urgent to develop cost-effective strategies of nitrogen management to overcome these obstacles. A 15-year experiment in annual double-cropping systems was conducted to explore impacts of N application rate and straw amendment on mineral N leaching loss in plastic-shed greenhouse. The results showed that seasonal mineral N leaching was up to 103.4–603.4 kg N ha−1, accounting for 12%–41% of total N input under conventional N fertilization management. However, optimized N application rates by 47% and straw addition obviously decreased mineral N leaching by 4%–86%, while had no negative impacts on N uptake and tomato yields. These large decreases of N leaching loss were mainly due to the reduced leachate amount and followed by N concentration in leachate, which was supported by improved soil water holding capacity after optimizing N application rates and straw addition. On average, 52% of water leachate and 55% of mineral N leaching simultaneously occurred within 40 days after planting, further indicating the dominant role of water leakage in regulating mineral N leaching loss. Moreover, decreasing mineral N leaching was beneficial for reducing leaching loss of base cations. Therefore, optimized N application rates and straw amendment effectively alleviates mineral N leaching losses mainly by controlling the water leakage without yield loss in plastic-shed greenhouse, making this strategy promising and interesting from environmental and economical viewpoints.

Effects of nitrogen application on the characteristics of mineral nitrogen leaching in purplish soil and spring maize yield in Sichuan

Effects of nitrogen application on the characteristics of mineral nitrogen leaching in purplish soil and spring maize yield in Sichuan

Benifits of biochar application for sandy loam Albic Luvisol

The effect of a slow pyrolisys biochar on the watercress ( Lepidium sativum L) root growth, on the sandy loam Albic Luvisol water retention, leachate acidity and mineral nitrogen leaching were studied in a six-week laboratory experiment. The experiment included four treatments: control soil; soil + biochar (20 t ha -1 ); soil + fertiliser (120 kg N ha -1 ); soil + biochar (20 t ha -1 ) + fertiliser (120 N kg ha -1 ). Spring wheat ( Triticum aestivum L) was sown to all the experimental pots. The soil in the pots was regularly watered to keep the water content at the field capacity level. When the wheat plants were strong with well-developed root systems, mineral fertiliser was added to the soil in liquid form according to the experiment setup. On the days 1, 3, 7, 14, 21, 28 and 41 after the fertilizer application high rates of water (400 cm 3 ) were applied to the soil. The leachate was collected and was tested for acidity (pH), available nitrogen in ammonium (N-NH 4 + ) and nitrate (N-NO 3 − ) forms. The water retention capacity of the soil samples was measured at water potentials between -5, and -300 kPa. The results have shown that the extract from the biochar had a stimulating effect on the watercress root growth. Water-holding capacity of the sandy loam Albic Luvisol was increasing after biochar application only at water potentials of –5 kPa and –10 kPa that corresponded to the soil capillary water. The studied biochar did not help in preventing N-NO 3 − or N-NH 4 + leaching from sandy loam Albic Luvisol.

Irrigation amount dominates soil mineral nitrogen leaching in plastic shed vegetable production systems

Flood irrigation and over fertilization lead to a large amount of nitrogen (N) leaching in conventional plastic shed vegetable production systems, resulting in low N use efficiency and huge environmental costs. Drip fertilization can significantly reduce N leaching by reducing irrigation and N application; however, the respective roles of each factor in reducing N leaching remain unknown. In this study, structural equation modeling was carried out to determine the direct and indirect relationships among factors related to N leaching in plastic shed tomato production across six consecutive growing seasons. Treatments were as follows: conventional flooding irrigation and fertilization (CIF); CIF + corn straw (CIF + C); CIF + wheat straw (CIF + W); drip irrigation and fertilization (DIF); DIF + corn straw (DIF + C); and DIF + wheat straw (DIF + W). The results showed that the most important contributing factor to N leaching in this study was water percolation, which is mainly controlled by irrigation amount. This suggests that irrigation amount has a greater effect than N input rate and straw addition. Compared to CIF, DIF significantly reduced N leaching by an average of 63.9% without compromising tomato yield, with significant increases of 52.9% and 28.1% in the water use efficiency (WUE) and partial factor productivity of applied N (PFPN), respectively. Meanwhile, application of straw also resulted in a significant reduction in N leaching by reducing water percolation, with wheat straw having a greater effect than corn straw. Overall, excessive irrigation rather than N input was found to be the main cause of significant N leaching, highlighting the importance of optimal irrigation schemes. We therefore recommend precise drip irrigation and fertilization combined with straw addition for sustainable and environmentally-friendly plastic shed vegetable production.

Comparison of the Agricultural Use of Products from Organic Waste Processing with Conventional Mineral Fertilizer: Potential Effects on Mineral Nitrogen Leaching and Soil Quality

Currently, there is an increasing emphasis on the use of renewable sources. The Czech Republic is no exception. There has been an increase in the number of biogas plants and composting plants. The main purpose of these facilities is to process organic wastes of various origins in order to utilize the waste, both for energy production and as soil fertility enhancers. Last but not least, the biogas station produces digestate, which could be further utilized. The present work deals with the assessment of the effect of digestate (doses of 220; 150 and 80 kg N ha−1), mineral fertilizer (150 kg N ha−1), and compost application (150 kg N ha−1) on selected indicators of soil environment: (a) soil microbial activity (basal and substrate-induced respiration); (b) plant nutrient content (P, K, Ca, Mg); (c) leaching mineral N from the soil; and (d) production of plant biomass of model plant Lactuca sativa L. Furthermore, the work aims to assess the individual doses of digestate and to determine the optimal one. The above effects were studied within a pot experiment for 63 days in controlled conditions. There were significant differences in Nmin leaching, which was significantly the highest in the variant with the application of a mineral fertilizer and lowest in variants with the application of digestate (variant 150 and 80 kg N ha−1) and compost (150 kg N ha−1). In terms of soil microbial activity, a significant effect of digestate application (150 kg N ha−1) on basal respiration versus the mineral fertilizer application was found (difference > 20%). This dose of digestate also had the highest positive effect on substrate-induced respiration, proven against all other variants, except for the digestate application at 220 kg N ha−1. Particularly, as compared with the mere application of mineral fertilizer, the application of digestate dose at 150 kg N ha−1 had the best positive effect on plant biomass production (+20%). On the other hand, compost application most positively affected the increase in available contents of nutrients and thus long-term soil fertility. Therefore, the dose of 150 kg N ha−1 digestate may represent an interesting alternative to increase actual soil fertility and thus to partially replace conventional mineral nutrition.

Post-harvest residues of field pea/oat mixtures as a source of biological nitrogen for hybrid winter rye

ABSTRACTThe conducted studies show post-harvest residues of sowing/pea mixtures limit leaching of mineral nitrogen deeper into the soil profile compared to post-harvest residues of sowing peas, as they affect the yield and amount of nitrogen accumulated in hybrid winter rye grain. The objective of the study was to determine the effect of the post-harvest residue biomass of field pea, oat and their mixtures on yielding and quantity of nitrogen accumulated in hybrid winter rye grain. Two factors were examined: factor I − post-harvest residues of field pea 100% − pure stand, oat 100% − pure stand, field pea 75% + oat 25%, field pea 50% + oat 50%, field pea 25% + oat 75%; factor II − forecrop harvest date: the stage of field pea flowering, the stage of field pea flat green pod. The obtained results demonstrated that the lowest mineral nitrogen content in two soil layers was recorded following oat harvested at the stage of field pea flat green pod. The research revealed that hybrid winter rye cultivated after the mixture consisting of 50% field pea and 50% oat should be recommended for wide agricultural application in order to obtain high grain yield.

Biochar Effects on Mineral Nitrogen Leaching, Moisture Content, and Evapotranspiration after 15N Urea Fertilization for Vegetable Crop

Globally, mineral nitrogen (N) losses as nitrate leaching (NL) are a substantial portion of applied fertilizer and cause surface and sub-surface water contamination. To precisely measure NL and its interlink parameters, biochar soil amendment was tested in this study. Three treatments—biochar (BC), without biochar (WB) with 15N urea (300 kg/ha), and control (no fertilization)—were tested in soil-filled lysimeters (circular PVC (Polyvinyl Chloride) tank of 30 cm diameter and 35 cm height) equipped with moisture content sensors and weighing assembly for the consecutive two cropping of Brassica Camprestis Var. Chinensis. The 15N-urea in the first season and the poultry manure in the second season were applied, but the fate of the 15N was examined in leachate, dry matter, and soil. As compared to WB, BC significantly decreased mineral N leaching, including nitrate levels (35%), increased electrical conductivity (68.5%), and water availability (20% inches per foot), while there was a non-significant increase in biomass per plant (2.84%), evapotranspiration (8.33%), dry matter (6.89%), and a decrease in mean leachate volume (7.63%). Moreover, BC accumulated values were higher than WB, as N uptake (38%), water use efficiency (12.24%), maximum fresh weight (11.4%), and soil N retained (185%) after cropping. The soil pH, the bulk density, and the total nitrogen were changed but presented non-significant differences. Therefore, biochar can increase soil N retention and available water to improve water use efficiency and decrease potential N leaching.

Mixed Intercropping of Wheat and White Clover to Enhance the Sustainability of the Conventional Cropping System: Effects on Biomass Production and Leaching of Mineral Nitrogen

The main goal of our research was to compare the mixed intercropping (MC) of winter wheat (Triticum aestivum) and white clover (Trifolium repens) with the sole cropping of Triticum aestivum, during two growing seasons (2012–2014), in a lysimetric experiment. We aimed to investigate the effect of the above growing system on total biomass production, grain yield and leaching of mineral nitrogen (Nmin). Four variants of intercropping (0 kg N/ha; 112 kg N/ha; 112 kg N/ha + 1.25 L of humic acids/ha; 70 kg N + 0.65 L of humic acids/ha) and two variants of sole cropping (0 kg N/ha; 140 kg N/ha) were used. Research results showed a good potential for growing wheat in the mixed cropping system without any negative effect on grain and total biomass production. No significant differences were found between the variants where winter wheat was grown with white clover (70 and 112 kg N/ha), and variants with sole wheat (140 kg N/ha), in both years of the experiment. The loss of Nmin from the soil was affected by the application of N fertilizer and mixed intercropping system. During the experiment, the loss of Nmin was higher by 20% in the variant using the sole winter wheat (140 kg N/ha), than in the MC variants.

El efecto de los polímeros absorbentes en la actividad microbiologica del suelo bajo condiciones mediterráneas

Objetivo. El objetivo de este estudio pasa por evaluar el efecto del-Terracottem- en la actividad microbiana del suelo mediante la medida de la respiración edáfica y la pérdida de nitrógeno mineral por lixiviación. El ensayo se ha realizado en condiciones de laboratorio controladas y con suelos naturales. Materiales y metodos. Para el experimento, se han diseñado varios tratamientos: i) suelos naturales a los que se les ha adicionado compuestos nitrogenados de libre disponibilidad (Kg N ha-1); ii) suelos naturales a los que se les ha adicionado carbohidratos de libre disponibilidad (1% de solución de glucosa); iii) suelos naturales a los que se les ha adicionado una mezcla de compuestos nitrogenados de libre disponibilidad (Kg N ha-1) con carbohidratos (1% de solución de glucosa). En cada variante se han testeado diferentes dosis del polímero. Resultados. Los resultados han demostrado que la actividad respiratoria del suelo es independiente de la disponibilidad de compuestos como el nitrógeno o carbono. Tampoco se han observado diferencias significativas entre las diferentes dosis del polímero. Por el contrario, si se observaron diferencias en la producción de CO2. Conclusiones. La lixiviación únicamente se producía cuando los suelos era enmendado con compuestos únicamente nitrogenados o únicamente sólo carbonosos.

The leaching of mineral nitrogen forms from light soil fertilized with compost and sewage sludge

The research was carried out in the years 2003-2013 in lysimeters filled with loamy sand. The leachate was tested in three variants: Z - no fertilization, S - 20 g-m-2 of N delivered annually in sewage sludge and C - 20 g-m-2 of N in the form of compost. The lysimeters were planted with Miscanthus giganteus, which is an energy plant with a high demand for water and nutrients. The amount of leaching of mineral nitrogen forms was determined on the basis of measured volumes of leachates from the soil and volumes of ammonium nitrogen (N-NH4) and nitrate nitrogen (N-NO3) contained in them. The research results showed a significant increase in the average content of mineral nitrogen forms in the effluents from the fertilized soil (S - 6.8 mg-dm-3 of N-NO3 and 0.3 mg-dm-3 of N-NH4, C - 7.8 mg-dm-3 of N-NO3 and 0.4 mg-dm-3 of N-NH4), compared to their concentrations in the leachates from non-fertilized soil (Z - 2.1 mg-dm-3 of N-NO3 and 0.2 mg-dm-3 of N-NH4). The content of mineral forms of nitrogen, in particular N-NO3, were similar in both fertilization variants. The lowest concentrations of mineral nitrogen in the leachates occurred in the third and fourth year after planting Miscanthus giganteus, when it entered the period of the highest yield. In the fifth year, due to a cold, snowless winter, there was a weakened growth of plants, which resulted in an increase in the concentration of mineral nitrogen in the leachates from the fertilized soil. It follows that in addition to the intensity of precipitation, the collection of this component by plants primarily influences nitrogen leaching from the soil. The general amount of mineral nitrogen leached from the soil was not large and amounted Z - 2.5 kg-m-2, S - 6.7 kg-m-2, C - 6.4 kg-m-2. This testifies to the intense collection of this form of nitrogen by Miscanthus giganteus.

The effect of time of winter urine deposition on mineral nitrogen leaching and implications for grazed forage crops

ABSTRACTTime of urine application on mineral N (Nmin) leaching from a pumice soil was tested. Artificial urine (600 kg N ha−1) was applied in early June or late July to small plots after removing a kale/swede crop or to ryegrass/white clover. Mineral N leached in the first winter (measured by porous cups, 600 mm deep) was similar under pasture or ex-forage crop: 185 vs. 60 kg N ha−1 for June or July urine, with 170–300 kg N ha−1 remaining in the soil (0–600 mm) at the end of drainage. Additionally, 54–118 kg N ha−1 leached in the second winter. In total, later application decreased Nmin leaching by 35–40%. Application of the process inhibitor dicyandiamide increased soil Nmin levels in the post forage crop site for the early urine application but had no effect in the late-applied urine treatment. There was no significant effect on N leaching.

Influence of soil structure on contaminant leaching from injected slurry

Animal manure application to agricultural land provides beneficial organic matter and nutrients but can spread harmful contaminants to the environment. Contamination of fresh produce, surface water and shallow groundwater with the manure-borne pollutants can be a critical concern. Leaching and persistence of nitrogen, microorganisms (bacteriophage, E. coli, and Enterococcus) and a group of steroid hormone (estrogens) were investigated after injection of swine slurry into either intact (structured) or disturbed (homogeneous repacked) soil. The slurry was injected into hexaplicate soil columns at a rate of 50 t ha−1 and followed with four irrigation events: 3.5-h period at 10 mm h−1 after 1, 2, 3, and 4 weeks. The disturbed columns delayed the leaching of a conservative tracer and microorganisms in the first irrigation event compared to the intact columns due to the effect of disturbed macropore flow paths. The slurry constituents that ended up in or near the macropore flow paths of the intact soil were presumably washed out relatively quickly in the first event. For the last three events the intact soil leached fewer microorganisms than the disturbed soil due to the bypassing effect of water through the macropore flow path in the intact soil. Estrogen leached from the intact soil in the first event only, but for the disturbed soil it was detected in the leachates of last two events also. Leaching from the later events was attributed to higher colloid transport from the disturbed soils. In contrast, NO3-N leaching from the intact soil was higher for all events except the first event, probably due to a lower nitrification rate in the disturbed soil. A week after the last irrigation event, the redistribution of all slurry constituents except NO3-N in most of the sections of the soil column was higher for the disturbed soil. Total recovery of E. coli was significantly higher from the disturbed soil and total leaching of mineral nitrogen was significantly lower from the disturbed soil. Results demonstrate how manure-borne constituents injected into undisturbed soil columns respond more as expected in the field, in terms of leaching and persistence, than do the same constituents injected into typically constructed columns of disturbed soil.

A slow release nitrogen fertiliser produced by simultaneous granulation and superheated steam drying of urea with brown coal

The inefficient use of nitrogen (N) fertiliser as a consequence of N losses from soil is a pressing issue in broad-acre agricultural systems. The research reported here tested the hypothesis that granulation of synthetic N fertiliser (urea) with a natural organic C resource (brown coal) would reduce fertiliser N loss from the soil system. Urea-enriched brown coal granules were simultaneously formed and dried within a pilot-scale superheated steam dryer. After application to unplanted soil columns, the urea-brown coal granules reduced nitrous oxide emission by up to 40 %, reduced mineral nitrogen leaching and maintained higher levels of N in topsoil when compared to conventional urea alone. Reduced gaseous N losses without a reduction in plant N uptake were also observed in planted soil columns treated with urea-brown coal granules. Brown coal-urea blended fertiliser showed potential for more efficient use of N in the long term and has environmental benefits in retaining more N in the soil.

Influence of Fertilization on Microbial Activities, Soil Hydrophobicity and Mineral Nitrogen Leaching

Abstract This work presents the analysis of the influence of compost and reclamation substrate addition and mineral fertilizers application on leaching of mineral nitrogen, microbial activities, soil hydrophobicity and plant biomass production. To demonstrate the effect of compost, reclamation substrate and mineral nitrogen (Nmin) addition on above parameters, the pot experiment was performed. As a model crop, Deschampsia caespitosa L. was used and cultivated for 63 days in climate chamber. The leaching of Nmjn was measured by application of ion exchange discs, soil hydrophobicity was determined based on the values of saturated hydraulic conductivity (Ksat) and microbial activity was expressed as basal (BR) and substrate induced respiration (SIR). Four variants (V1-V4) with different doses of fertilizers were prepared: V1 - control without addition of fertilizers; V2 - this variant of experiment was prepared as mixture of compost and arable land in ratio 7:3; V3 - 90 g/m2 of mineral fertilizers NPK (in the ratio 1:1:1) were applied there and into V4, dose 30 g of compost were applied. The significant differences (P < 0.05) in the detection of Nmin, values of Ksat and SIR were found. The highest decrease of mineral nitrogen leaching was observed by the simultaneous applications of compost (V4) to arable soil, about 50% in comparison with the variant V4 (application of mineral fertilization) and about 10% in comparison with the control. Variants with addition of compost (V2 and V4) showed higher values than variants without, which were measured at three stages (before application of Nmin - 12 days after establishment of the experiment; after application of Nmin - 34 days; at end of the experiment - 63 days). During the experiment, two types of respiration were measured: BR and SIR. The significant differences in SIR were found between variants with addition of compost and variants without. The SIR (cumulative production of CO2) was higher about 25% in variants V2 and V4 compared to variants V1 and V3. The highest values of Ksat were found in variants with addition of compost. Conversely, the lowest value of Ksat was detected in variant with addition of Nmin. Low values of Ksat indicate an increased level of hydrophobicity.

The efficiency of nutrient utilization by permanent grassland in the Kameničky locality

This work presents the analysis of the effect of grassland management on leaching of mineral nitrogen from rhizosphere and plant biomass production in area of our interest. The determined values show the influence of fertilization and species composition of permanent grassland on leaching of mineral nitrogen and biomass production. The values were determined during field and laboratory experiments. The highest availability of Nmin in the field experiment was detected in the variant N90+PK; the lowest availability of Nmin was recorded in the PK variant. The difference was statistically significant (P < 0.05). In the pot experiment, the highest loss of Nmin was recorded in the variant with N180+PK (16.88 mg.dm−3) with the difference being statistically significant as compared with the other variants (P < 0.05). Measured values of the availability of mineral nitrogen and plant biomass production indicate the importance of species composition at the establishment of new grassland. For example, species composition of permanent grassland has a great importance at the establishment of new grassland on erosion-affected soils in protection areas of drinking water. Because selected species of grasses can immobilize nitrogen in their bodies, thus preventing it’s leaching from the soil.

Evaluating Fertilizer Application Strategy for Improving Crop Yields and Reducing Mineral Nitrogen Leaching in High Rainfall Areas of Taiwan

A 2-yr pot experiment conducted on an upland sandy clay loam soil in National Taiwan University, Taipei evaluated crop yields and mineral nitrogen (Nmin) leaching as affected by fertilizer application strategy, viz., inorganic (100% N from urea), organic (100% N from compost), combined (compost plus urea) and a zero control (Ctrl) treatments. Cabbage (Brassica oleracea L.) and corn (Zea mays L.) were grown in annual rotation under simulated high rainfall conditions. The Nmin leaching was monitored adding 83 and 62 mm of water fortnightly to cabbage and corn respectively for a total of 28 times. One-way ANOVA was used to determine the statistical significance of treatment effect and Tukey test for means comparisons (p = 0.05). Treatment differences were subtle for dry matter yields (DMY) but the treatments were strikingly different for 2-yr cumulative Nmin leaching (6.66% in organic, 30.6% in inorganic and 8.10% in combined treatments). This difference was largely related to the ability of soil to an increased retention of added N under organic and combined fertilization treatments. Unlike reported elsewhere, N recoveries were relatively high in compost applied soils, with or without urea fertilizer application. It is concluded that framers’ practices of fertilization that has inherent problem of excessive N leaching in high rainfall areas of Taiwan could be improved by proper compost and urea combinations within agronomically recommended rate of N application.DOI: http://dx.doi.org/10.3126/njst.v12i0.6472 Nepal Journal of Science and Technology 12 (2011) 7-16

Nutrient and carbon balances in organic vegetable production on an irrigated, sandy soil in northern Oman

AbstractOur understanding of nutrient and carbon (C) fluxes in irrigated organic cropping systems of subtropical regions is limited. Therefore, leaching of mineral nitrogen (N) and phosphorus (P), gaseous emissions of NH3, N2O, CO2, and CH4, and total matter balances were measured over 24 months comprising a total cropping period of 260 d in an organic‐cropping‐systems experiment near Sohar (Oman). The experiment on an irrigated sandy soil with four replications comprised two manure types (ORG1 and ORG2) characterized by respective C : N ratios of 19 and 25 and neutral detergent fiber (NDF)‐to‐soluble carbohydrates (SC) ratios of 17 and 108. A mineral‐fertilizer (MIN) treatment with equivalent levels of mineral N, P, and potassium (K) served as a control. The three treatments were factorially combined with a cropping sequence comprising radish (Raphanus sativus L.) followed by cauliflower (Brassica oleracea L. var. botrytis) or carrot (Daucus carota subsp. sativus). Over the 24‐months experimental period gaseous N emissions averaged 45 kg ha–1 (59% NH3‐N, 41%N2O‐N) for MIN, 55 kg N ha–1 (69% NH3‐N, 31%N2O‐N) for ORG1, and 49 kg N ha–1 (59% NH3‐N, 41% N2O‐N) for ORG2. Carbon losses were 6.2 t ha–1 (98% CO2‐C, 2% CH4‐C) for MIN, 9.7 t C ha–1 (99% CO2‐C, 1% CH4‐C) for ORG1, and 10.6 t ha–1 (98% CO2‐C, 2% CH4‐C) for ORG2. Exchange resin–based cumulative leaching of mineral N amounted to 30 kg ha–1 for MIN, 10 kg ha–1 for ORG1, and 56 kg ha–1 for ORG2. Apparent surpluses of 361 kg N ha–1 and 196 kg P ha–1 for radish‐carrot and 299 kg N ha–1 and 184 kg P ha–1 for radish‐cauliflower were accompanied by K deficits of –59 kg ha–1 and –73 kg ha–1, respectively, for both cropping systems. Net C balances for MIN, ORG1, and ORG2 plots were –7.3, –3.1, and 1.5 t C ha–1 for radish‐carrot and –5.0, 1.3, and 4.6 t C ha–1 for radish‐cauliflower. The results underline the difficulty to maintain soil C levels in intensively cultivated, irrigated subtropical soils.