Journal Articles
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Item A low-cost simple lysimeter soil retriever design for retrieving soil from small lysimeters(IOP Publishing, 2024-06-06) Gunaratnam A; McCurdy M; Grafton M; Jeyakumar P; Davies CE; Bishop PItem Iron-rich sand promoted nitrate reduction in a study for testing of lignite based new slow-release fertilisers(Elsevier, 20/12/2022) Abhiram G; Grafton M; Jeyakumar P; Bishop P; Davies C; McCurdy MMThe N losses and agronomic performances of newly developed slow-releasing fertilisers (SRFs; Epox5 and Poly5) were tested against conventional N fertilisers, urea and diammonium phosphate (DAP), in a climate-controlled lysimeter system. The dry matter (DM) yield and N losses of SRFs were not significantly different from urea and DAP. However, nitrate leaching and nitrous oxide (N2O) losses were unexpectedly low and therefore, it was inferred that nitrate underwent a chemical transformation. It was observed that a thick fibreglass wick interrupted drainage and created an anaerobic condition in the soil. The subsoil was found to have a high extractable total iron and it was postulated that iron played a role in the observed low level of N losses. An investigation was carried out with a factorial design using sand types and rates of N application as the main factors. Two types of sand; with high and low iron concentration and four levels of N applications; 0 (control), 50, 100 and 200 kg N ha-1 were employed in a leaching column and nitrate and N2O losses were measured. The nitrate leaching was significantly (P < 0.05) affected by sand types wherein a lower nitrate level was recorded for high‑iron concentration sand than for low-iron concentration sand at all N application levels. The N2O emission was significantly (P < 0.05) lower for high-iron sand than for low-iron sand for the 200 N treatment, but not significantly different between sand types for other treatments. These observations provide evidence for the involvement of iron in nitrate transformation under anaerobic conditions and it was hypothesised path was dissimilar nitrate reduction (DNR). Further studies are recommended, to identify the underlying mechanism responsible for nitrate reduction with iron-rich sand.Item Capability of ground fertiliser placement when spread from a fixed wing aircraft(13/04/2016) Chok S; Grafton M; Yule IJ; Manning MAerial topdressing using differential rate application technology improves fertiliser spreading on hill country farms. However, the system’s ability to place fertiliser accurately and precisely within an area needs to be determined. Accuracy was determined by comparing measured and intended application rates. Precision was indicated by the coefficient of variation (CV), which is the standard deviation of the measured application rate over the mean of this rate. Two trials were carried out, where aircraft deposited fertiliser at two application rates and fertiliser was captured using cone-shaped collectors. The average measured application rate for both trials was less than the intended rate. The CV ranged from 35 to 57%, and was lower than CV’s from pilot-operated hopper systems (78%). A one-way analysis of variance test found the difference between measured application rate in the high and low application zone was statistically significant. The results indicate work is required to improve the accuracy and precision of the differential rate system, however, the system shows promise. Keywords: differential rate application technology, aerial spreading, fertiliser placement
