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Mass balance modelling often shows that leaching is the main loss pathway for cadmium (Cd) from agricultural soils. There is however a scarcity of Cd leaching data measured under field conditions to support these modelled losses. This study used passive-wick fluxmeters installed at a depth of one metre at six commercial cropping sites to measure Cd in drainage over one year of monitoring. Cadmium concentrations were generally below the method detection limit (0.05 µg Cd L−1) for all sites, with only the occasional detection from two sites and no detection from three other sites. The exception was site A where average Cd concentrations ranged from 0.06 to 0.18 µg L−1 and the mean annual loss (± SE) was 0.33 ± 0.08 g Cd ha−1. This was similar to the amount estimated using the drainage flux multiplied by a modelled estimate of soil solution Cd concentrations for the site, 0.41 g Cd ha−1. Cadmium balance models typically assess the rate of Cd accumulation in the 0–7.5 or 0–30 cm soil depth. Further studies are still required to obtain Cd leaching data collected under field conditions at these soil depths to allow modelled Cd leaching to be validated against measured data. [ABSTRACT FROM AUTHOR]

The global demand to increase food production from underperforming, water and nutrient limited soils is increasing, which has resulted in an increased dependency on water for irrigation. As fresh water is a finite resource, the increase in irrigation use has resulted in competition between water used for municipal purposes and that used for food and fibre production for an increasing global population. An opportunity exists to improve the efficiency of both urban and agricultural systems by taking green waste compost generated in urban centres and incorporating it into agricultural soils with poor water retention, thereby increasing the ability of these soils to efficiently retain irrigation water for plant use and also to capture a greater volume of water from rainfall. Addition of amendments to soil changes the pore space. The magnitude and cause for this change depends on amendment type, application rate, soil type and climatic conditions. The aim of this research was to determine if the incorporation of municipal compost (MC) can increase the quantity (total volume) and concentration (total volume per unit volume) of soil pores that hold readily available water (defined as macro-mesopores of 30-3 pm diameter) and plant available water (defined as mesopores of 30-0.3 [micro]m diameter). We hypothesised that increases in total porosity would be positively correlated with MC application rate and increases in water holding porosity (macro-mesoporosity and mesoporosity) would be positively correlated with decreasing MC particle size due to the creation of inter-particle pore spaces < 30 [micro]m in diameter. The MC was screened to three different maximum particle sizes--MC4 ( Additional keywords: municipal compost, pore volume, porosity, soil, water. Received 21 June 2019, accepted 25 November 2019, published online 18 December 2019, Introduction Globally, there is increasing demand for fresh water, which presents a challenge as water is a finite resource. Crop irrigation currently consumes 70% of global water extractions, making it [...]

Commercial cropping farms in New Zealand (NZ) showed highly variable rates of nitrate-N leaching losses (13–148 kg/ha/year) across sites, cropping systems and seasons. Losses were measured at 1.2 m below the soil surface using a network passive-wick drainage fluxmeters (DFMs) which were installed across nine commercial farms between August 2014 and June 2016. Sites were located in the Canterbury, Manawatu, Hawke's Bay, Waikato and Auckland regions and monitored for a period 51 to 72 months. Twelve DFMs were installed at each site and drainage volumes were validated using an established soil water balance model. At seven sites, losses were calculated using measured drainage and measured concentrations, and at two sites losses were calculated using modelled drainage and measured concentrations. Nitrate-N was the predominant form of inorganic N (96.7–99.9%) in drainage water and annual losses averaged 52 kg/ha/yr for mixed cropping systems with livestock grazing (n = 6) and 101 kg/ha/yr for mixed cropping systems with a focus on vegetable production (n = 3). While not broadly representative of all NZ cropping land uses, results from this study do, nevertheless, suggest that when drainage occurs, nitrate losses may be considerable under the land uses represented here (> 70 kg/ha/y). [ABSTRACT FROM AUTHOR]

Field trials conducted in the Waikato region over three summer seasons (2007–08, 2008–09 and 2009–10) evaluated whether soil nitrogen (N) reserves at sites previously under long-term pasture and with a history of regular farm dairy effluent application were sufficient for maize production with either minimal or no additional N fertiliser inputs. Crop productivity was assessed in the first (six trials) and second (two trials) years following cultivation of pasture. In first year trials there were no productivity differences between no fertiliser control treatments (NF) and treatments receiving an application of starter fertiliser (SF) or starter and side dress fertiliser (SSF). In second year trials the SF treatment maximised yield at one site, but none was required at the other. Crop yields were high across all trials (22.9–31.9 t DM/ha). Results confirmed that in most cases there was adequate soil N to maximise crop productivity without the need for fertiliser inputs. Despite high crop N uptake, soil mineral N levels remained elevated (109–227 kg N/ha) at four sites after cropping, an observation attributed to high rates of mineralisation during the summer. There were few correlations between pre-plant soil tests and the amount of N mineralised at these sites. [ABSTRACT FROM AUTHOR]