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| 1 | The current status of nitrogen fertiliser use efficiency and future research directions for the Australian cotton industry显示文摘Fifty years of sustained investment in research and development has left the Australian cotton industry well placed to manage nitrogen(N) fertiliser. The average production in the Australian cotton industry today is greater than two tonnes of lint per hectare due to improved plant genetics and crop management. However, this average yield is well below the yield that would be expected from the amount of N fertiliser used. It is clear from the recent studies that across all growing regions, conversion of fertiliser N into lint is not uniformly occurring at application rates greater than 200-240 kg·hm^(-2) of N. This indicates that factors other than N availability are limiting yield, and that the observed nitrogen fertiliser use efficiency(NFUE) values may be caused by subsoil constraints such as sodicity and compaction. There is a need to investigate the impact of subsoil constraints on yield and NFUE.Gains in NFUE will be made through improved N fertiliser application timing, better targeting the amount of fertiliser applied for the expected yield, and improved soil N management. There is also a need to improve the ability and confidence of growers to estimate the contribution of soil N mineralisation to the crop N budget. Many Australian studies including data that could theoretically be collated in a meta-analysis suggest relative NFUE values as a function of irrigation technique; however, with the extensive list of uncontrolled variables and few studies using non-furrow irrigation, this would be a poor substitute for a single field-based study directly measuring their efficacies. In irrigated cotton, a re-examination of optimal NFUE is due because of the availability of new varieties and the potential management and long-term soil resilience implications of the continued removal of mineralised soil N suggested by high NFUE values. NFUE critical limits still need to be derived for dryland systems. | MACDONALD Ben C.T. LATIMER James O. SCHWENKE Graeme D. NACHIMUTHU Gunasekhar BAIRD Jonathan C. | 2018 | Journal of Cotton Research2018，1，3： | 5 |
| 2 | A review of phosphorus nutrition in irrigated cotton farming systems of Australia显示文摘Australian cotton production predominantly occurs on Vertisols.The average lint yield of cotton grown in Australia is 2260–2700 kg·hm^(−2),which is 2.5 to 3 times the world average.This high productivity per unit of land area requires efficient use of resources such as water and nutrients.However,high yields accelerate the export of nutrients such as phosphorus(P)in seed,depleting the soil reserves of P more than in other countries with lower cotton yields.Recent surveys of cotton industry indicate that P application rates should match seed P export(30~40 kg·hm−2),but historical depletion within subsoil is still evident and is continuing.Depletion of soil P is typically more pronounced in the subsoil than in the topsoil(0~20 cm)where P fertiliser is applied,as cotton roots rely on these layers as important sources of plant available water and available P.This mismatch between zones of P uptake and resupply may increase stratification of available P in the soil profile.Recent studies showed that cotton responded poorly to banded applications of fertiliser P,while dispersal of fertiliser throughout the plant beds was more successful.Researchers have also observed sporadic cotton responses to applied P fertiliser in soils where available P concentrations were well above the previously determined critical concentrations indicative of fertiliser P responses in Australia.To sustain highyielding cotton production in Australia,a greater understanding of cotton root acquisition of applied P,as well as a re-examination of critical soil P concentrations for each production region are required. | NACHIMUTHU Gunasekhar SCHWENKE Graeme MERCER Clarence BISCHOF Callum HULME Pat BELL Michael | 2022 | Journal of Cotton Research2022，5，1： | 2 |
| 3 | Structure and Microstructure of Ion-Plated Titanium Films显示文摘 | Gunasekhar K R Srinivasulu S Swarnalatha M | 1994 | Thin Solid Films1994，252，： | 1 |
| 4 | Effect of oxygen partial pressure on the structural and optical properties of dc reactive magnetron sputtered molybdenum oxide films显示文摘 | V. Nirupama K.R. Gunasekhar B. Sreedhar S. Uthanna | 2009 | Current Applied Physics2009，，1： | 1 |
| 5 | Structure and microstructure of ion- plated titanium films 显示文摘 | Gunasekhar K R Srinivasulu S Swarnalatha M | 1994 | Thin Solid Films1994，252，： | 1 |
| 6 | Effect of oxygen partial pressure on the structural and optical proper- ties of de reactive magnetron sputtered molybdenum oxide films显示文摘 | Nirupama V Gunasekhar K R Sreedhar B | 2010 | Curr Appl Phys2010，10，1： | 1 |
| 7 | Structure and microstructure of ion-plated titanium films显示文摘 | Srinivasulu S Swarnalatha M | 1994 | Thin Solid Films1994，252，： | 1 |
| 8 | Structure and microstructure of ion-plated titanium films显示文摘 | Srinivasulu S Swarnalatha M | 1994 | Thin Solid Films1994，252，： | 1 |
| 9 | Structure and microstructure of ion-plated titanium films显示文摘 | Gunasekhar K R Srinivasulu S Swarnalatha M | 1994 | Thin Solid Films1994，252，： | 1 |
| 10 | On-farm gains and losses of soil organic carbon in terrestrial hydrological pathways:A review of empirical research显示文摘Theoretical estimates of soil carbon sequestration in Australian farming systems often do not coincide with measured values of soil carbon,possibly due to post sequestration carbon losses.Carbon loss through soil erosion is one of several pathways of sequestered carbon loss from agricultural systems.Specific details on different loss pathways,especially carbon loss through terrestrial hydrological pathways on a farm scale,are sparse.In this article,we review the Australian and global literature on terrestrial on farm carbon gains and losses in hydrological pathways.Catchment scale,landscape scale and modelling studies are not the focus of this review and are only briefly addressed.Carbon fractions associated with soil erosion and runoff include particulate organic and inorganic carbon,dissolved organic carbon(DOC),dissolved inorganic carbon(DIC),dissolved CO_(2)-C and dissolved CH4-C.Temperate climatic zones with approximately 500 mm of annual rainfall may receive from 6.4 to 29.5 kg ha^(−1) of DOC in rainfall(with concentration of 1.28-5.9 mg L^(−1) of DOC in rainwater).Carbon addition(net)to a field through irrigation water can range from 4.6 to 30.8 kg ha^(−1).The carbon losses through runoff and erosion may vary from below detection limits to 1072 kg ha^(−1) yr^(−1) and these values are significant proportions of SOC sequestration rates reported in literatures.Organic carbon enrichment ratios in eroded sediments range from 0.39 to 5.Total organic carbon concentrations in deep drainage below farming lands range from negligible to 90 mg L^(−1).Management practices that may influence soil carbon losses in erosion and runoff include changing land use,tillage,ground cover,farm layout and slope,furrow length and vegetative buffer strips in the tail end of the field.The literature surveyed indicated that a large knowledge gap existed in Australia with respect to empirical data on soil carbon lost through erosion and runoff because most studies focussed on nutrients other than carbon.The new carbon farming initiative measure means,a better understanding on the farm level carbon losses through runoff across different farming systems is essential to better predict the SOC sequestration potential.Other gaps include carbon losses in the form of carbon dioxide and methane emissions associated with the irrigation network(head ditches,tail drains etc.),on farm water bodies and sediment depositional sites,farm level carbon gains through irrigation and flooding.Carbon losses in deep drainage and its impact on whole soil profile denitrification and the associated mechanisms and biochemical changes of carbon,and carbon and nitrogen interactions during on-farm transport and storage within on-farm dams needs further investigation. | Gunasekhar Nachimuthu Nilantha Hulugalle | 2016 | International Soil and Water Conservation Research2016，4，4： | 0 |
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