Search

The objective of this laboratory incubation study was to assess the effectiveness and longevity of urease inhibitor N-(2-nitrophenyl) phosphoric triamide (2-NPT), along with the commonly used N-(n-butyl) thiophosphoric triamide (nBTPT), in reducing ammonia (N[H.sub.3]) emissions from cattle urine applied to pasture soils. It was hypothesised that 2-NPT would be effective as a longer-lasting inhibitor to reduce emissions after the deposition of urine during multiple grazing events. Two dairy-grazed pasture soils (Fluvisol, Rangitikei loamy sand (RLS) and Andosol, Egmont black loam (EBL)) with contrasting organic carbon levels and urease activity were used. The following treatments were applied to the soils at the start of the experiment: no inhibitor, nBTPT-low, 2-NPT-low, 2-NPT-medium and 2-NPT-high. Urine-N was applied to all the treatments at four stages: immediately before inhibitor application (Stage A), 29 days after inhibitor application (Stage B), 56 days after inhibitor application (Stage C) and 29 days and again 60 days after inhibitor application (Stage D); N[H.sub.3] emissions were measured up to Day 31 after each urine application. The low, medium and high application rates of inhibitors were determined based on achieving 0.025%, 0.050% and 0.075% of quantity of urine-N applied in Stage A respectively. For the no inhibitor treatment, the proportion of total applied N in urine that was emitted as N[H.sub.3] for the different stages ranged from 35.8% to 50.5% for RLS soil and from 14.2% to 26.7% for EBL soil. For Stage A, both inhibitors equally reduced N[H.sub.3] emissions from applied urine in both soils (23.7-27.3% for the RLS and 20.6-27.2% for the EBL). For Stage B, significant reductions (4.2-13.4%) in N[H.sub.3] emitted was observed only from RLS soil, with there being a significantly greater reduction from 2-NPT than from nBTPT, and 2-NPT continued to reduce N[H.sub.3] emissions at Stage C (5.6-7.4%). There was no reduction in emissions during Stage D by either of the inhibitors. The results of this study suggest that 2-NPT can extend the longevity of urease inhibition and reduce N[H.sub.3] emissions compared with the more commonly used inhibitor nBTPT in dairy-grazed pasture soils. Additional keywords: dairy soils, environmental degradation, nitrogen loss, nitrogen use efficiency, soil pH, urea hydrolysis. Received 11 November 2018, accepted 31 May 2019, published online 23 July 2019, Introduction The intensification and expansion of dairy farming in New Zealand (NZ) over the past three decades has resulted in a significant rise in the amount of cattle urine being [...]

Micronutrients copper (Cu) and zinc (Zn) have the potential to inhibit soil urease activity (UA) and reduce ammonia (N[H.sub.3]) emissions over long duration (8-12 weeks) but have not been tested for reducing N[H.sub.3] losses from cattle urine deposited in dairy-grazed pasture soils. The objective of this study was to assess the effectiveness and longevity of Cu and Zn in reducing soil UA, for the use of these metals to reduce N[H.sub.3] emissions from deposited urine by grazing cattle. A series of experiments were conducted to (i) assess the relationship between inherent Cu and Zn status and soil UA of New Zealand dairy-grazed pasture soils, (ii) determine the impact of Cu and Zn addition to pasture soils on soil UA and (iii) investigate how soil organic carbon (C) and other C-related textural and mineralogical properties such as clay content and cation exchange capacity influence the effectiveness of added Cu and Zn in reducing urea hydrolysis. The results showed significant positive correlations of soil total C and total nitrogen (N) with soil UA. However, there were no significant negative correlations of soil UA with inherent Cu and Zn levels. Similarly, addition of Cu and Zn to soil did not significantly reduce soil UA. However, when Cu was added to two different soil supernatants there was a significant reduction in hydrolysis of urea applied at 120 and 600 mg urea-N [kg.sup.-1] soil. Additions of Zn achieved negligible or small reductions in urea hydrolysis after 120 and 600 mg urea-N [kg.sup.-1] soil applications to soil supernatants. This result suggests that Cu can inhibit soil UA and urea hydrolysis in soil supernatants with potentially low C, clay and cation exchangeable base contents. However, the interaction of bioavailable Cu with labile soil organic C and clay particles leads to its inactivation, resulting in ineffectiveness in organic C-rich pasture soils. Although most of the added Zn did not complex and remained bioavailable, the observed levels of bioavailable Zn had limited effect on soil UA. Additional keywords: ammonia emissions, clay content and cation exchange capacity, metal bioavailability, nitrogen loss, nitrogen use efficiency, soil organic carbon, urease inhibition., Introduction Intensification of dairy farming in New Zealand (NZ) over the last three decades has resulted in a substantial increase in the national dairy herd size from 2.3 million cows [...]

The increasing number of satellite missions provides vast opportunities for continuous vegetation monitoring, crucial for precision agriculture and environmental sustainability. However, accurately estimating vegetation traits, such as nitrogen concentration (N%), from Landsat 7 (L7), Landsat 8 (L8), and Sentinel-2 (S2) satellite data is challenging due to the diverse sensor configurations and complex atmospheric interactions. To address these limitations, we developed a unified and physically based method that combines a soil–plant–atmosphere radiative transfer (SPART) model with the bottom-of-atmosphere (BOA) spectral bidirectional reflectance distribution function. This approach enables us to assess the effect of rugged terrain, viewing angles, and illumination geometry on the spectral reflectance of multiple sensors. Our methodology involves inverting radiative transfer model variables using numerical optimization to estimate N% and creating a hybrid model. We used Gaussian process regression (GPR) to incorporate the inverted variables into the hybrid model for N% prediction, resulting in a unified approach for N% estimation across different sensors. Our model shows a validation accuracy of 0.35 (RMSE %N), a mean prediction interval width (MPIW) of 0.35, and an R 2 of 0.50, using independent data from multiple sensors collected between 2016 and 2019. Our unified method provides a promising solution for estimating N% in vegetation from L7, L8, and S2 satellite data, overcoming the limitations posed by diverse sensor configurations and complex atmospheric interactions. [ABSTRACT FROM AUTHOR]

Plantain (Plantago lanceolata L.) is a forage that produces secondary metabolites with one, aucubin, known to inhibit soil nitrification. This study aimed to quantify the exudation of aucubin and catalpol by plantain root systems in a hydroponic experiment; evaluate the effect of aucubin on nitrogen (N) leaching and nitrous oxide (N2O) emissions from urine applied to plantain and ryegrass-white clover swards; and compare N losses from a ryegrass-white clover sward after urine from cows fed plantain and cows fed ryegrass-white clover was applied. Nitrate ( NO 3 − ) leaching and N2O losses were measured in a lysimeter experiment. Catalpol, but not aucubin, was exudated by plantain roots. N2O emissions were decreased by plantain swards and by ryegrass-white clover swards to which aucubin was also applied. Aucubin had no effect on NO 3 − leaching. Urine from cows grazing plantain had no effect on N2O emissions, and N leaching when compared to the urine from cows grazing ryegrass-white clover with the same N content. We conclude the plantain sward and the aucubin applied to the ryegrass-white clover sward decreased N2O emissions via mechanisms in the soil separate from the decreased emissions resulting from the lower N concentration of urine derived from cows grazing plantain. [ABSTRACT FROM AUTHOR]

Extremely acidic soils have low pH, high concentration of exchangeable Al3+ and low cation exchange capacity (CEC) that cause severe growth for most plants. The study was conducted in the soil laboratory of the Indonesian Vegetable Research Institute, Lembang, from June to August 2019. A randomised complete block design with seventeen treatments, three replications, and three incubation times (3, 30 and 60 days) was deployed to assess the effect of rates of soil amendments, namely 5 to 30 t liming materials ha-1, 5 to 20 t rice husk biochar ha-1, and 5 to 20 t zeolite ha-1 on extremely acidic soils. The results showed that lime materials, i.e., lime, agriculture limestone, and hydrated lime had a similar effect on increasing soil pH and reducing exchangeable Al3+. Calcium super seemed more effective in increasing soil pH and reducing exchangeable Al3+ than local lime due to the high CCE value. However, there was no significant response to the highest rice husk biochar and zeolite rate on soil pH and exchangeable Al3+. Rice husk biochar increased the concentration of K+ and zeolite raised the concentration of Na+. However, the effect was minimal. About 3 t lime ha-1 or 2.5 t calcium super ha-1 or equivalent to 1.5 to 2 times exchangeable Al3+ is required to obtain the soil pH target of 4.8, where the exchangeable Al3+ was less than 0.5 cmol(+) kg-1. [ABSTRACT FROM AUTHOR]

Nitrification inhibitors can reduce nitrous oxide (N2O) emissions and nitrate leaching losses from agricultural soils. Technologies have been developed to detect and target urine patches for inhibitor application, thereby reducing the total amount of inhibitor used. However, in practice there will be a time delay between the urine deposition and inhibitor application, potentially leading to physical separation of the inhibitor and urine that could reduce the effectiveness of the inhibitor compared to when the inhibitor and urine are well mixed. In this study, 2L of cattle urine was applied on two soil types in New Zealand. Twenty-four hours later the inhibitor dicyandiamide (DCD) was applied. The soil was sampled within 18 h and again after a rainfall event. DCD concentrations were measured in the 0–20 mm, 20–50 mm, and 50–100 mm depth ranges. The movement of the urine in the soil was simulated using the HYDRUS model. Before the rain most of the DCD was within the top 20 mm and intercepted 21–29% of the urine. After the rainfall event the DCD concentration decreased in the 0–20 mm layer and increased in the 20–50 mm layer. 18–55% or 63-79% of the urine was intercepted by DCD at a concentration of >4 ppm using the measured and modelled DCD concentrations, respectively. However, only 0–27% or 0-53% of the urine was intercepted at a DCD concentration >10 ppm. [ABSTRACT FROM AUTHOR]

This article reviews the literature on nitrate leaching under sheep grazing systems and focuses on identifying future research needs. Urinary nitrogen (N) is an important source of the nitrate leached from pastoral agriculture. Urinary N excretion can be measured or simulated using models and has been well characterised for dairy systems. It is difficult to continuously monitor the urinary N excretion of sheep under field conditions; consequently, measurements of N excretion in sheep urine are limited. Urination events by sheep vary greatly in volume (0.5 L to 6.9 L), concentration (3 to 13.7 g N/L), and frequency (8 to 23 events/day); this variation results in a corresponding variation in N loading rates in urine patches. The amount of nitrate leached under pastures grazed by sheep has typically varied between 1 and 50 kg N/ha/year, but rates as high as 300 kg N/ha/year have been reported. The quantity of nitrate leached under sheep depends on the season, climate, quantity and timing of drainage, the interaction between forage production and stocking rate, fertiliser applied, N fixation by legumes, forage type, and grazing management. The majority of studies examining nitrate leaching under sheep grazing systems are more than 20 years old; so, there is little recent information on nitrate leaching under modern pasture-based sheep production systems. Further research is required to quantify nitrate leaching levels under current sheep farming practices, to understand the impacts of this leaching on water quality, and to help identify effective strategies to reduce the transfer of N from grazed paddocks to receiving water bodies. This additional information will help provide information for decision support tools, including models and management practices, to help sheep farmers minimise their impact on the aquatic environment. [ABSTRACT FROM AUTHOR]

The annual quantities of nitrate-N (-N) and total N (TN) leached from mole and pipe drained dairy pastures on a Pallic soil, were reduced by an average of 52% and 42% (p < .05), respectively, by standing cows off pasture to ruminate and rest after grazing (Duration-controlled grazing, DC), compared to the standard grazing management (SG) of leaving cows at pasture between milkings. For the SG treatment, measured -N leached was 13, 8 and 21 kg N ha−1 and total N leached was 18, 13 and 26 kg N ha−1 in 2009, 2010 and 2011, respectively. Annual surface runoff contained <1 kg -N ha−1 y−1 and <3 kg TN ha−1 y−1. The deposition of urine in the autumn period had the greatest influence on the quantity of leached in winter drainage. DC grazing is a practical method to reduce N leaching from grazed dairy pastures. [ABSTRACT FROM AUTHOR]

Standing cows off pasture after 4 hours of grazing (duration-controlled (DC) grazing) was researched over 3 years (2008-2011) to compare the losses of nutrients in drainage and surface runoff water with losses under standard grazing (SG). Pasture growth rates, nutrient concentrations and apparent intake by cows were used to model nutrient removals from, and returns to, pasture. Pre- and post-grazing covers and apparent pasture intakes were similar for both treatments. Quantities of N, P and K returned to the DC plots in excreta and effluent were 34%, 0% and 45% less than those returned to SG plots. This reduction in nutrient returns was associated with a nil, 20% and 9% decrease in annual pasture growth on the DC plots in the three respective years. Reductions in annual pasture growth under DC grazing may be avoidable if nutrient removals are balanced with returns in effluent and fertiliser. [ABSTRACT FROM AUTHOR]

Spring cultivation of soil under long-term pasture to grow summer forage followed by autumn pasture renewal is a common practice on New Zealand dairy farms. Although this practice is widely used, there is limited research available on the impact that it has on nutrient losses to water. This three-year field study was conducted to quantify the effects of summer forage cropping and autumn re-grassing on nitrogen (N) and phosphorus (P) losses in mole and pipe drainage from a Pallic Soil in the Manawatu region of New Zealand. The two treatments compared were a continuation of long-term grazed pasture, and long-term pasture that was cultivated in spring, sown into turnips as a summer forage for dairy cows, followed by autumn re-grassing. Both treatments where located on artificially drained field plots. Summer forage cropping and autumn re-grassing increased total nitrogen measured in drainage water by 21 kg N/ha in total over the three seasons monitored, which was a 84% increase compared to long-term pasture. Approximately three-quarters of this increase happened during the two months following spring cultivation, which was influenced by an atypically wet late spring/early summer period that extended the drainage season. It is estimated that if the spring cultivation had been conducted in a year with a more typical drainage season, then the additional total nitrogen losses are likely to have been about 6.9 kg N/ha. Overall losses of total phosphorus in drainage were low for both treatments during the study period, with the forage cropping and autumn re-grassing increasing total phosphorus losses in drainage by 0.36 kg P/ha over the duration of the study, which was 77% higher than the long-term pasture treatment. [ABSTRACT FROM AUTHOR]

To assist the adoption of biochar production as a greenhouse gas mitigation technology, evidence is required that biochar can provide additional economic benefits covering its current cost of manufacture. Biochar has the potential to be used as sorbent for NH4+-N removal from wastewaters. Two batch studies were conducted to compare (i) sorption of NH4+-N on pine biochars with different particle sizes and (ii) sorption of NH4+-N on pine biochar in comparison to alternative sorbents, zeolite (clinoptilolite) and pine bark. Decreasing the particle size of the feedstock (pine chip), or the biochar by crushing after pyrolysis, did not affect its NH4+-N sorption properties. Sorption of NH4+-N on comparative sorbents, when added at a dose of 39 mg NH4+-N L−1, followed the order zeolite > biochar > bark. Zeolite proved to be the most efficient sorbent for NH4+-N g−1 removal followed by biochar and bark. Biochar has the potential to be used as a cost effective commercial sorbent for removing NH4+-N from waste streams. [ABSTRACT FROM AUTHOR]

Simple Summary: Plantain (Plantago lanceolata) has emerged as a forage with the ability to reduce nitrogen (N) losses, in particular N leaching, from grazing dairy systems. For farmers to confidently incorporate plantain into their farms, research needs to demonstrate that these environmental benefits sustain similar production and farm profit than traditional ryegrass (Lolium perenne)–white clover (Trifolium repens, wc)-based pasture. The effect of changing the cows' diet to plantain-based pastures was evaluated over two lactation seasons in comparison to ryegrass–wc pastures. Cows grazing plantain-based pastures produced the same milk solids production, but a urine with a lower N concentration when compared to ryegrass–wc pastures. Plantain reduced the urinary N loads from individual urine patches via higher urine volume and reduced the total N loading onto pastures via a lower urinary N excretion to mitigate the N leaching losses from grazed pastures. Plantain pastures could be employed by farmers to reduce the nitrate leaching from dairy farms. The use of plantain pasture in dairy systems can potentially reduce nitrogen (N) leaching losses via the lower N concentration in the urine (UNc) of cows. Reducing the urinary N load while cows graze pastures can reduce the risk of N leaching losses from urine patches. Research needs to demonstrate that these environmental benefits are not at the expense of milk production and farm profit. Three groups of 20 cows grazed in the following three pasture treatments: (i) plantain, (ii) plantain–clover mix (plantain, red [Trifolium pratense] and white clover), or (iii) ryegrass-white clover (wc) pastures, from spring to autumn for two years. Each year, pasture intake, diet quality, milk production and animal N (milk and urine) excretion were evaluated in spring, summer, and autumn. The cows grazing the plantain and plantain–clover mix pastures produced similar milk solids as cows grazing ryegrass–wc pasture but reduced their UNc during summer and autumn, when compared to those grazing the plantain–clover mix and ryegrass–wc pastures. Plantain reduced urinary N loads onto pastures by a greater number of urine patches with lower urinary N loading rates. The results demonstrate that plantain pastures do not diminish milk solids production from cows, and the lower UNc from summer to autumn could reduce N being lost to the environment. [ABSTRACT FROM AUTHOR]

Abstract: In the design of wood-based, enhanced-denitrification bioreactors to treat nitrate in agricultural drainage, the consideration of the highly variable flow rates and nitrate concentrations inherent to many drainage systems is important. For optimized mitigation of these nitrate loads, it may be best to contain drainage water prior to treatment in order to facilitate longer, more constant retention times rather than to allow cycles of flushing and dry periods in the denitrification bioreactor. Simulated containment prior to bioreactor treatment compared to passing drainage directly through a bioreactor was investigated with the use of six pilot-scale denitrification bioreactors constructed with plywood and filled with Pinus radiata woodchips at Massey University No. 4 Dairy Farm (Palmerston North, New Zealand). Initial bromide tracer tests were followed with a series of five simulated drainage events each at successively declining inflow nitrate concentrations. During each drainage event, three pilot bioreactors received a simulated hydrograph lasting 1.5 days (Non-Containment treatment) and three pilot bioreactors received the same total drainage volume treated over 4 days at a constant flow rate (i.e. constant retention time; Containment treatment). Results showed significantly different total mass removal efficiencies of 14.0% vs. 36.9% and significantly different removal rates of 2.1gNm−3 day−1 vs. 6.7gNm−3 day−1 for the Non-Containment and Containment treatments, respectively, which indicated that treating drainage at constant retention times provided more optimized nitrate removal. While this work was done to evaluate treatment under New Zealand drainage conditions, it also provides valuable information for optimizing agricultural drainage denitrification bioreactor performance in general. [Copyright &y& Elsevier]

This paper summarises findings from the Pathogen Transmission Routes Research Program, describing pathogen pathways from farm animals to water bodies and measures that can reduce or prevent this transfer. Significant faecal contamination arises through the deposition of faeces by grazing animals directly into waterways in New Zealand. Bridging of streams intersected by farm raceways is an appropriate mitigation measure to prevent direct deposition during herd crossings, whilst fencing stream banks will prevent access from pasture into waterways by cattle that are characteristically attracted to water. Riparian buffer strips not only prevent cattle access to waterways, they also entrap microbes from cattle and other animals being washed down-slope towards the stream in surface runoff. Microbial water quality improvements can be realised by fencing stock from ephemeral streams, wetlands, seeps, and riparian paddocks that are prone to saturation. Soil type is a key factor in the transfer of faecal microbes to waterways. The avoidance of, or a reduction in, grazing and irrigation upon poorly drained soils characterised by high bypass flow and/or the generation of surface runoff, are expected to improve microbial water quality. dairyshed wastewater should be irrigated onto land only when the water storage capacity of the soil will not be exceeded. This "deferred irrigation" can markedly reduce pollutant transfer to waterways, particularly that via subsurface drains and groundwater. advanced pond systems provide excellent effluent quality and have particular application where soil type and/or climate are unfavourable for irrigation. Research needs are indicated to reduce faecal contamination of waters by livestock. [ABSTRACT FROM AUTHOR]