Identifying Sustainable Nitrogen Management Practices for Tea Plantations

Tea (Camellia sinensis L.) is the most widely consumed beverage in the world. It is mostly grown in the tropics with a heavy dependence on mineral nitrogen (N) fertilisers to maintain high yields while minimising the areas under cultivation. However, N is often applied in excess of crop requirements, resulting in substantial adverse environmental impacts. We conducted a systematic literature review, synthesising the findings from 48 studies to assess the impacts of excessive N application on soil health, and identify sustainable, alternative forms of N management. High N applications lead to soil acidification, N leaching to surface and groundwater, and the emission of greenhouse gases including nitrous oxide (N2O). We identified a range of alternative N management practices, the use of organic fertilisers, a mixture of organic and inorganic fertilisers, controlled release fertilisers, nitrification inhibitors and soil amendments including biochar. While many practices result in reduced N loading or mitigate some adverse impacts, major trade-offs include lower yields, and in some instances increased N2O emissions. Practices are also frequently trialled in isolation, meaning there may be a missed opportunity from assessing synergistic effects. Moreover, adoption rates of alternatives are low due to a lack of knowledge amongst farmers, and/or financial barriers. The use of site-specific management practices which incorporate local factors (for example climate, tea variety, irrigation requirements, site slope, and fertiliser type) are therefore recommended to improve sustainable N management practices in the long term.

A novel amended nitrification inhibitor confers an enhanced suppression role in the nitrification of ammonium in soil

Purpose Nitrification inhibitor plays an important regulatory role in inhibiting the nitrification of ammonium in soils. However, most of nitrification inhibitors lack the sustainable effects in suppressing the nitrification of ammonium. In this study, a novel DMS nitrification inhibitor was prepared and tested to explore its lasting effect of nitrification suppression in black soil. Materials and methods Both culture experiments and field trial were performed in black soils. Three kinds of nitrification inhibitors (NIs), dicyandiamide (DCD) with low bioactivity, 3,4-dimethylpyrazole phosphate (DMPP) with high bioactivity, and a novel 3,4-dimethylpyrazole sulfate zinc (DMS) with long half-life, were applied into soils, respectively, and the abundance changes of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) were investigated; then, the accumulation changes of inorganic nitrogen, nitrogen use efficiency, and crop yields were furtherly evaluated. Results and discussions A novel DMS nitrification inhibitor with high activity and long half-life maintained a persistent effect of nitrification suppression, and remarkably increased the accumulation of ammonium nitrogen in soil, thus improving nitrogen use efficiency and crop yields. This study implies that lowering the nitrogen loss of nitrification-triggered in soil is of great importance for improving nitrogen use efficiency. Conclusions This study provided an insight into the sustainable nitrification suppression of a novel DMS nitrification inhibitor under excessive application of nitrogen fertilizer in black soils. Compared with improving the activity, reasonably prolonging the validity of nitrification inhibitors in soil is a more important strategy increasing the sustainable effects of nitrification inhibition, and the survival period of nitrification inhibitors in soil should be a crucial factor improving nitrogen use efficiency.

EFFECT OF FERTILIZERRS WITH UREASE AND NITRIFICATION INHIBITORS ON DURUM WHEAT CROP ON YIELD AND QUALITY (Triticum turgidum L. subsp. durum)

Conventional agricultural has a significant role in climate change. For this reason, farmers choose more innovative practices such as fertilizers inhibitors. Durum wheat (Triticum turgidum L. subsp. durum) is the most cultivated winter crop in the Mediterranean basin. The scope of this study is to determine the improvement of the fertilizer yield by adding nitrification (DMPSA) and urease (NBPT) inhibitor in urea in durum wheat crop. Meridiano variety was evaluated for one growing period through 2019–2020 under two basic fertilization (20-20-0 and 12-40-0 (+10S +Zn). The experiments were designed according to split-plot design, 2 main plots (basic fertilization) and 7 subplots (top fertilization). The top fertilization were the various urea combination treatments (urea, urea + urease inhibitor thiophosphoric-triamide (NBPT) (UI), urea + nitrogen inhibitor 3,4- dimethylpyrazole succinic (DMPSA) and control. Nitrogen markers, such as nitrogen use efficiency (NUE), nitrogen harvest index and nitrogen agronomic efficiency (NAE) were used to evaluate nitrogen release. The length of the inflorescences was over 20 cm for all fertilizations. Regarding basic fertilization, larger inflorescences were recorded with 12-40-0 (+10S +Zn). The grain protein content and nitrogen were higher by 1-2% under basic basic fertilization 20-20-0. Grain and biomass production were increased with both fertilizers’ inhibitors (NBPT and DMPSA). Between two inhibitors, urease inhibitor (NBPT) yielded higher than DMPSA.

Dairy Industry under New Zealand's Emissions Trading Scheme: Analysis of Farmers' Attitudes towards Climate Change: The Expense Created by the NZETS and the Point that Farmers will Begin to Reduce Emissions

<p>Adaptation to actual climate change and contingency planning to reduce vulnerability from likely climate change effects is crucial for the New Zealand dairy industry. Thus in alignment with international treaties and growing international pressure and speculation, the New Zealand Government in October 2007 announced an Emissions Trading Scheme (ETS) adaptable specifically to the New Zealand scene. This ETS passed into law in September 2008 through the enactment of the Climate Change Response (Emissions Trading) Amendment Act 2008. This thesis specifically looks at agriculture related emissions and calculates the liability faced by the dairy industry come 2013 when the industry is completely involved in the ETS. The purpose of this is to further aid the industry so that it can best align itself with the ETS in order to minimise this liability. This is not simply an aid to help the industry save money, as the minimisation of liability should come as a benefit to the environment through reduced emissions. There is also a second issue associated with this - as to whether the liability faced by the industry will be material enough in order for the farmers to actually mitigate their environmental impacts or will they simply bear the expense and ignore the opportunities to reduce their emissions against a baseline (and potentially generate carbon credits for sale) and/or offset any residual emissions through purchasing carbon credits? This therefore analysed the threshold of farmer's incomes whereby they will choose to abate their emissions rather than simply paying for their carbon emissions liability. This threshold obviously varied greatly through the dairying industry with differing factors - this was taken into account and discussed in detail. Other aspects influence this threshold also, factors such as the opportunity for the industry to market a niche product if they do achieve a low carbon or carbon neutral status for their products, cost competitiveness of available abatement technologies, geographical issues pertaining to each abatement method and so on. In order to gain an insight into farmers' perceptions 23 Taranaki dairy farmers were interviewed. This 23 was selected randomly from a list of farmers who reside in the geographical area of Taranaki. This randomisation allowed for an analysis of a variety of size of farmers which eliminated a bias of perceptions from dominating farming sizes within this region. Utilising the theoretical framework surrounding stabilisation triangles, riparian management and nitrification inhibitors were the basis of this examination for emissions reduction management due to their major co-benefit of improved water quality alongside the ultimate goal of emissions reductions. The extent of potential mitigation through the implementation of riparian management and nitrification inhibitors equates to two of the wedges required for the overall reduction in emissions under the ETS. Also, as explained earlier, the co-benefit of improved water quality associated with riparian management and nitrification inhibitors make their implementation even more attractive. The theory behind riparian management and nitrification inhibitors has mostly been done, therefore for the purpose of this thesis, farmers' perceptions of the abatement options were examined. These perceptions included the associated opportunities as well as the challenges that will be faced by those participating farmers.</p>

Dairy Industry under New Zealand's Emissions Trading Scheme: Analysis of Farmers' Attitudes towards Climate Change: The Expense Created by the NZETS and the Point that Farmers will Begin to Reduce Emissions

<p>Adaptation to actual climate change and contingency planning to reduce vulnerability from likely climate change effects is crucial for the New Zealand dairy industry. Thus in alignment with international treaties and growing international pressure and speculation, the New Zealand Government in October 2007 announced an Emissions Trading Scheme (ETS) adaptable specifically to the New Zealand scene. This ETS passed into law in September 2008 through the enactment of the Climate Change Response (Emissions Trading) Amendment Act 2008. This thesis specifically looks at agriculture related emissions and calculates the liability faced by the dairy industry come 2013 when the industry is completely involved in the ETS. The purpose of this is to further aid the industry so that it can best align itself with the ETS in order to minimise this liability. This is not simply an aid to help the industry save money, as the minimisation of liability should come as a benefit to the environment through reduced emissions. There is also a second issue associated with this - as to whether the liability faced by the industry will be material enough in order for the farmers to actually mitigate their environmental impacts or will they simply bear the expense and ignore the opportunities to reduce their emissions against a baseline (and potentially generate carbon credits for sale) and/or offset any residual emissions through purchasing carbon credits? This therefore analysed the threshold of farmer's incomes whereby they will choose to abate their emissions rather than simply paying for their carbon emissions liability. This threshold obviously varied greatly through the dairying industry with differing factors - this was taken into account and discussed in detail. Other aspects influence this threshold also, factors such as the opportunity for the industry to market a niche product if they do achieve a low carbon or carbon neutral status for their products, cost competitiveness of available abatement technologies, geographical issues pertaining to each abatement method and so on. In order to gain an insight into farmers' perceptions 23 Taranaki dairy farmers were interviewed. This 23 was selected randomly from a list of farmers who reside in the geographical area of Taranaki. This randomisation allowed for an analysis of a variety of size of farmers which eliminated a bias of perceptions from dominating farming sizes within this region. Utilising the theoretical framework surrounding stabilisation triangles, riparian management and nitrification inhibitors were the basis of this examination for emissions reduction management due to their major co-benefit of improved water quality alongside the ultimate goal of emissions reductions. The extent of potential mitigation through the implementation of riparian management and nitrification inhibitors equates to two of the wedges required for the overall reduction in emissions under the ETS. Also, as explained earlier, the co-benefit of improved water quality associated with riparian management and nitrification inhibitors make their implementation even more attractive. The theory behind riparian management and nitrification inhibitors has mostly been done, therefore for the purpose of this thesis, farmers' perceptions of the abatement options were examined. These perceptions included the associated opportunities as well as the challenges that will be faced by those participating farmers.</p>

Plant Nitrogen Uptake From Insect Frass Is Affected by the Nitrification Rate as Revealed by Urease and Nitrification Inhibitors

Insect protein production is considered a sustainable alternative to livestock protein which furthermore utilizes waste streams. Its production can have positive but also potentially negative environmental effects, which require evaluation. Frass, the byproduct of insect production, is regarded an efficient organic fertilizer or soil amendment. However, several studies report negative frass effects on plant growth and nitrogen (N) cycling. Therefore, a pot trial was carried out which sought to understand N release from frass and subsequent growth and nutrient uptake of Italian ryegrass. Mealworm frass (MWF) or buffalo worm frass (BFW) was applied at two rates (1.5 and 3% w/w) to a soil-sand mix. To evaluate N release processes, frass was applied alone, with a nitrification inhibitor (NI), a urease inhibitor (UI), or both (NI+UI). Plant N, nutrient uptake and soil inorganic N were measured at the experiment's end. To gauge whether altered N fluxes induced changes in the microbial community, soil microbial biomass, bacterial/archaeal abundances and ergosterol content as a fungal biomarker, were determined. Both frass types and application rates stimulated microbial growth and N mineralization. The 3% rate inhibited seed germination, possibly due to salinity or ammonia toxicity. At the 1.5% rate, both frass types were effective fertilizers. MWF led to higher biomass and nutrient uptake, owing to its higher extractable nutrient concentrations. The 3% rate caused nitrite accumulation in the absence of NI. NI improved plant biomass, nutrient uptake, stimulated archaeal and bacterial abundances and prevented nitrite accumulation. UI reduced N mineralization, showing that a substantial fraction of frass organic N is ureic. UI enhanced fungal contribution to the microbial biomass, revealing the importance of bacteria in frass N mineralization processes when UI is not applied. NI and UI combined, induced greater N release from frass than UI or NI alone. Our study demonstrated the usefulness of NI and UI in studying N release from frass. NI can improve plant N uptake and minimize N losses following frass application, reducing its potentially negative effects. UI can retard N release from frass, allowing its application as a slow-release fertilizer, but should not be used concurrently with NI.