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ABSTRACTThree different grassed-down apple orchard production systems (organic or biological, BFP; conventional, CFP; and integrated, IFP) in New Zealand were compared for their effects on some important soil physical, chemical and biological quality parameters. A total of 17 grassed-down apple orchards with alley and treeline areas from BFP, CFP and IFP systems in experimental sites and two commercial (organic and conventional) orchards were studied. At each orchard, soils were sampled at three depths (0–50, 50–150, 150–300 mm) in the treeline and alley and were analysed for soil physical properties (soil bulk density, SBD; and soil infiltration rate, IR). Samples from the top two depths (0–50 and 50–150 mm) were also analysed for soil chemical (pH, P, K, Ca, Mg, S) and biological (earthworm number, fresh biomass and composition; microbial biomass C, BC; microbial biomass N, BN; CO, evolution) parameters. Earthworm parameters were determined to a depth of 0.25 m.In general, significantly lower SBD and higher IR occurred in treeline than alley in all orchards due to soil compaction by orchard vehicles in the alley. The BFP treeline and commercial organic orchard showed lowest SBD and highest IR. Soil chemical parameters were found to be related to nutrient management practices imposed such as increased K and S in BFP treelines due to pea straw additions. Returns of mown clippings from alleys to treelines enhanced nutrient transfers and increased nutrient levels in treelines of BFP and IFP orchards.Earthworm number and biomass were sensitive indicators and were high in pea straw-treated treelines of BFP orchards due to substrate additions. Although earthworm biomass varied in the alleys between orchards, high earthworm numbers occurred in most orchard alleys. Highest number of earthworm species were found in BFP and commercial organic orchards. The measured soil respiration (CO2evolution) showed significant differences between soil depths but no significant differences between orchard systems except in one site where BFP showed higher CO2evolution than IFP or CFP. The BC and BN were significantly higher in commercial organic than conventional orchards and in topsoils than subsoils in about half of the orchards studied. Overall, sensitive soil quality indicators found, capable of distinguishing between orchard management treatments, were SBD, IR, earthworm number, fresh biomass and composition while those which distinguished between topsoils and subsoils were CO2evolution, BC and BN.

ABSTRACTMajor objectives of this study were to evaluate the effects of organic, conventional and integrated orchard fruit production systems on the quality and quantity of soil organic matter in orchard floors and to identify sensitive soil organic matter indicators. Seventeen different soil organic matter parameters were studied. These were soil aggregate stability (AS), total nitrogen (TN), total carbon (TC), carbon/nitrogen ratio, microbial biomass N (BN), microbial biomass C (BC), BC:BN; BC:TC; BN:TN; hot-water extractable C (HC), hot-water extractable carbohydrate (HCA), HCA:HC; humin N (hum N), humin C (hum C), hum C:TC; hum N:TN and potentially mineralizable N (Pot N). They were based largely on soil organic matter characteristics and fractions extracted sequentially by different extractants from soils collected from the alleys and treelines of organic, conventional, and integrated grassed-down apple orchard types from both commercial and experimental sites in Canterbury, New Zealand. A total of 12 apple orchards were investigated. Soil samples collected from these orchards (0–75 mm depth) were analysed for TC, TN, BC, BN, Pot N, AS and also sequentially extracted for labile and stable soil organic matter fractions using cold and hot water, acid mixtures (hydrochloric:hydroflouric acids, HC1:HF) and alkalis (sodium pyrophosphate and sodium hydroxide, Na4P207and NaOH). Only TN, BN, and BN:TN showed significant interaction effects and all these were associated with soil N. Overall, combining orchards according to similar management systems, results obtained showed no significant differences between experimental and commercial orchards. However, sensitive indicators capable of distinguishing significant differences between different orchard management systems were BC, BC:TC and HCA:HC while HCA:HC distinguished significantly between treelines and alleys within each group of the same orchard type.

AbstractThe effects of two organic (blood and bone, compost) and two inorganic (potassium nitrate, KNO3; ammonium sulphate, (NH4)2SO4) forms of nitrogen (N) fertilisers on the yield and some quality indices of tomatoes were studied in a pot experiment using Waimairi peaty loam soil obtained from an area currently used for vegetable production. Four rates (0,150, 300, 600 kg N/ha, based on soil bulk density) of each fertiliser form were used. Fruit yield was significantly correlated with foliage N concentration, but not with fruit N concentration. Increasing rates of all N fertilisers, except compost, produced significant increases in fruit yield. Compared with the control, at 600 kg N/ha applied, compost increased fruit yield by 40% only whereas the other N fertilisers studied increased fruit yield by 120%. Fruit quality indices measured showed variable response to treatments. Fruit colour increased significantly on application of blood and bone, (NH4)2SO4, and KNO3, whereas compost showed no effect. Fruit vitamin C concentrations decreased when all N fertilisers were applied. Increasing N rate produced significant negative linear trends with vitamin C concentration decreasing by 18–28% depending on the form applied. Fruit size was unaffected by treatments but visual quality of fruit decreased when N in any form was applied.

Quaternary loess deposits containing charcoal and in situorganic matter constituents from Banks Peninsula, New Zealand, were subjected to various physical and chemical treatments before radiocarbon assay. A stepwide procedure was used in which each component was radiocarbon dated before and after the treatments were applied. The criterion adopted for judging the effectiveness of a treatment is an increase in the radiocarbon age of loess layer. On this basis the oldest and therefore the most reliable date was obtained from the intra-loess charcoal and its humic acid extract. By comparison, the radiocarbon ages of organic matter constituents of the whole or partitioned loess were much younger, and are considered to represent only average ages for the particular layers concerned. No advantage was gained by dating the carbon-enriched clay-humus fraction as opposed to whole loess samples. There is an apparent conflict between our dates and current interpretation of loess stratigraphy and chronology in the South Island of New Zealand, which requires further investigation. This uncertainty apart, the upper layers of multiple loess deposits are clearly much older than earlier reports indicate, and it follows that the correlation of these deposits with late-glacial events both within and beyond New Zealand is even more tenuous and unreliable than previously thought to be the case.