Soil compaction-induced physical degradation is a threat to sustainable crop production and environmental performance. While measures have been evaluated to alleviate compaction, the impact of catch crops establishment on soil physical recovery following winter grazing remains underexplored. Six New Zealand trials over different years investigated: (1) the effects of soil compaction induced by winter forage crop grazing on soil health, and (2) the effectiveness of catch crops establishment in facilitating soil recovery. Our findings revealed that winter grazing resulted in significant soil physical degradation in the top 10 cm, evidenced by significant reduction in total porosity, macroporosity, available water content, saturated hydraulic conductivity (Ks), and soil quality S index. The degree of soil degradation was higher under increased grazing intensity (fodder beet grazing compared with kale grazing) and wetter conditions. For example, in Te Pirita-2019 with kale, changes in Ks were not significant. However, in Te Pirita-2019 with fodder beet, Ks decreased significantly from 1548 mm day-1 to 88 mm day-1, representing a 94.3 % reduction. Compared with fallow after grazing, growing catch crops promoted soil restoration. Conventional moldboard ploughing and the recently introduced single-pass 'spaderdrill' outperformed direct drill for soil recovery. This study highlighted the importance of catch crop establishment using conventional tillage and spade drill to mitigate soil degradation resulting from winter forage crop grazing. The spader-drill, where soil conditions allow, is preferred because it allows earlier sowing of catch crops, leading to broader benefits such as increased crop biomass and reduced nitrogen leaching.

Eight oats catch crop trials were conducted over two years on winter forage paddocks on commercial dairy farms in Canterbury and Southland measuring the effect of tillage and timing-by-tillage, respectively, on dry-matter (DM) yields, N uptake and profitability (gross profit margin). The main objective was to successfully integrate catch crops into winter forage rotations over a critical period when the soil is normally bare and the potential for N drainage loss from urinary-N deposition is high. Oat harvest yields at green-chop silage maturity (similar to 50% panicle emergence) ranged from 8 to 10 t DM/ha when sown by the end of winter (4-5 months after drilling). Nitrogen uptakes ranged from 52 to 363 kg N/ha. Net gross profit typically ranged from NZ$1000 to NZ$1600/ha (assuming revenue of NZ$0.20/kg DM for standing feed). Minimum-till cultivation produced higher DM yields than direct-drill treatments in both years of the Canterbury trials (similar to 30% higher overall) but where N availability and good soil-seed contact were maintained, differences in yield were small (similar to 5%). Earlier sowing in Southland using a spader-drill combination increased DM yields and N uptake overall by 123% and 48%, respectively, over later sown conventional tillage options.

Accurate measurements of the change in total flower count, and the ratio of opened to closed flowers per inflorescence with time, play an important role in studying phenological changes of inflorescences over time. The duration of flowering has an important role in the resulting fruitset and yield. Automation of the flower counting process with inflorescence images, using image processing and morphological tools, is a challenging problem. This is because it involves the processing of images with varying image qualities, and also because of the close similarity in images between the two classes of interests, opened and closed flowers. Our aim is to build a system with one of the most promising deep learning object detection networks, Mask R-CNN, to detect the individual instances of the above two classes separately using the images with no prior alterations. The system should be tested with the images taken with different illumination levels, different backgrounds, and with different scales. Our system was tested with images taken in three consecutive flowering seasons (2018, 2019 and 2020) and showed promising results. These tests also highlighted areas that can be improved to ensure better accuracy.

Safe operation of automated robotic platforms in environments where humans also work require on-board sensors that can accurately and robustly detect humans in the environment so that appropriate action can be taken. This is a challenging problem in unstructured outdoor environments as most sensors are negatively affected by changing environmental conditions like ambient light and moisture. Our aim is to use a combination of thermal and visible colour images to detect humans in forest environments. The system should be able to work through dense foliage and should not be confused by other objects that generate heat like machines or other animals. We developed and tested a system on a data-set of sensor data collected in a similar outdoor environment but with synthetic targets added to highlight the ability of the system to be robust to severe optical occlusion in dense vegetation and to the presence of hot machines that could fool the thermal sensor. Our initial results show promise and also highlight where improvements can be made with further testing in more realistic forest environments.

A series of S-band radar scans of grape vines conducted over the growing season is presented. Despite covering the time frame from early development of grape berries to harvest, there is minimal observable change in the radar imagery. This observation along with theory of scattering demonstrate that microwave glare from shoots is the dominant feature in the imagery.

Growing winter forages, such as brassicas and fodder beets, is a common feed strategy to build body condition for non-lactating cows, prior to calving, in the temperate regions of New Zealand. However, the large quantities of feed grown, ~14-20 tonnes ha-1, and resulting high stocking rates, means large volumes of urine are deposited during grazing, over relatively small areas, on cool, bare and often wet soils. These conditions create a high potential for large N leaching losses. Sowing a catch crop might be one way to mitigate this potential but most catch crops are sown in late-summer/autumn, not late winter/spring, so this study’s objectives were to examine the potential of a cold-tolerant cereal, oats, to establish and take up soil N over this period.

Winter grazing of fodder beet and kale is common practice in many regions of New Zealand. However, large quantities of urine-nitrogen (N) is returned by livestock onto bare soil during grazing at a period when the risk of drainage is high. Results from recent field trials in the Canterbury region show that sowing a catch crop directly after winter forage grazing can reduce N leaching losses by up to 49% compared with fallow soil, as well as offer significant gains in feed production, via additional annual production from the catch crop. However, the magnitude of effectiveness varies in response to crop management, catch crop genotype, soil type and seasonal weather conditions. For example, early-sown cereal genotypes adapted to lower temperatures provide the greatest potential to reduce leaching. This summary also highlights three important areas for future research: (i) overcoming the practical challenges of establishing catch crops in unfavourable conditions, (ii) development of biophysical models that can predict outcomes over a wide range of production systems and conditions, and (iii) quantification of other processes in the N cycle causing changes in N leaching, e.g. microbial immobilisation of N.

Intensive winter forage grazing systems have a high risk of environmental impact due to nitrate ( NO- 3) leaching from urine deposition on cool, wet, fallow soils. We investigated the effect of sowing two catch crops after simulated winter forage grazing on kale to potentially reduce N leaching losses from a winter application of labelled 15N- urine ( 350 and 700 kg N ha- 1) using field lysimeters. The experiment measured the capture of N by the sowing at recommended dates of either oats ( Avena sativa) or Italian ( It.) ryegrass ( Lolium multiflorum) and the resulting 15N balance. Results showed that the sowing of an oats catch crop reduced nitrate leaching by 25% over the critical winter- spring drainage period compared with It. ryegrass. Relatively small amounts of the labelled 15N- urine ( 3- 4%) were captured in the catch crops of urine treatments so the reduced nitrate leaching under the oats crop was attributed to lower drainage over the period.

Our review concludes that organic standards need to account for a broader set of criteria in order to retain claims to ‘sustainability’. Measurements of the ecological, economic and social outcomes from over 96 kiwifruit, sheep/beef and dairy farms in New Zealand between 2004 and 2012 by The Agricultural Research Group on Sustainability (ARGOS) project showed some enhanced ecosystem services from organic agriculture that will assist a “land-sharing” approach for sustainable land management. However, the efficiency of provisioning services is reduced in organic systems and this potentially undermines a “land-sparing” strategy to secure food security and ecosystem services. Other aspects of the farm operation that are not considered in the organic standards sometimes had just as much or even a greater effect on ecosystem services than restriction of chemical inputs and synthetic fertilisers. An organic farming version of the New Zealand Sustainability Dashboard will integrate organic standards and wider agricultural best practice into a broad and multidimensional sustainability assessment framework and package of learning tools. There is huge variation in performance of farms within a given farming system. Therefore improving ecosystem services depends as much on locally tuned learning and adjustments of farm practice on individual farms as on uptake of organic or Integrated Management farming system protocols.

Grazing of winter forage crops is a common management option used in the dairy industry of New Zealand, particularly in the South Island, where they are used to feed nonlactating, pregnant dairy cows prior to calving. However, there is concern that the large crop yields per hectare grazed, combined with a high stocking density of cows, lead to large amounts of urinary nitrogen (N) deposited on bare, wet soil that, in turn, could lead to large nitrate leaching losses. We report the results of a simulated winter forage grazing event using field lysimeters planted with a kale (Brassica oleracea L.) crop. The effect of sowing a 'catch crop' of oat (Avena sativa L.) following the simulated winter forage grazing on nitrate leaching losses from urine applied at different times throughout the winter was measured. A catch crop sown between 1 and 63 days after the urine deposition in early winter reduced N leaching losses from urine patches by similar to 34% on average (range: 19-49%) over the winter-spring period compared with no catch crop. Generally, the sooner the catch crop was sown following the crop harvest, the greater the uptake of N by the catch crop and the greater the reduction in nitrate leaching losses. The results indicate that sowing of a catch crop following winter crop grazing could be an effective management strategy to reduce nitrate leaching as well as increase the N-use efficiency of dairy winter forage grazing systems.

A cut-and-carry trial was conducted on a low Quick-test-potassium (QTK ≤4) Lismore soil during 2012-13 in Springston, Canterbury to test the responsiveness of a dairy pasture to urine, dicyandiamide (DCD) and potassium (K) applications. Over the full year the applications of urine-only, urine+K, urine+DCD, and urine+DCD+K increased pasture production significantly over the non-urine control treatment by 23%, 29%, 36% and 42%, respectively.. Applications of K, DCD and DCD+K increased production over the urine-only treatments by 5%, 10% and 15%, respectively, for both spring and full-year totals. There were no significant increases to K or DCD applications for non-urine treatments. The pasture responses to K and DCD applications were attributed to maintaining better balanced plant nutrition, rather than to soil K deficiency per se, as urine application maintained QTK levels to recommended values (QTK ~6) for the duration of the trial. However, K deficiency may still have occurred at times of high demand where K uptake was restricted by the shallow soil depth. Whilst these differences were considered to have their roots, at least partly, in K nutrition, it may also reflect differences that are particular to cutand-carry trial management and measurement. Continual harvesting of DM reduces K availability quickly in some soils even after large initial K applications in urine (>800 kg K/ha). The findings of this cut-and-carry trial show that regular K application can increase pasture DM responses both to applied urine-N and the use of a nitrification inhibitor, and not just when soil K levels are low.

A cut-and-carry trial was conducted on a low quick-test potassium (QTK <= 4) Lismore soil during 2012-13 in Springston, Canterbury to test the responsiveness of a dairy pasture to urine, dicyandiamide (DCD) and potassium (K) applications. Over the full year the applications of urineonly, urine + K, urine + DCD, and urine + DCD + K increased pasture production significantly over the non-urine control treatment by 23%, 29%, 36% and 42%, respectively. Applications of K, DCD and DCD + K increased production over the urine-only treatments by 5%, 10% and 15%, respectively, for both spring and full-year totals. There were no significant increases to K or DCD applications for non-urine treatments. The pasture responses to K and DCD applications were attributed to maintaining better balanced plant nutrition, rather than to soil K deficiency per se, as urine application maintained QTK levels to recommended values (QTK c. 6) for the duration of the trial. However, K deficiency may still have occurred at times of high demand where K uptake was restricted by the shallow soil depth. Although these differences were considered to have their roots, at least partly, in K nutrition, it may also reflect differences that are particular to cut-and-carry trial management and measurement. Continual harvesting of dry matter (DM) reduces K availability quickly in some soils even after large initial K applications in urine (>800 kg K/ha). The findings of this cut-and-carry trial show that regular K application can influence pasture DM responses to the urine-nitrogen retained in soil, and to the use of a nitrification inhibitor, and not just when soil K levels are low.

Thank you for the opportunity to respond to Dr Edmeades’ criticisms of our paper ‘Pasture dry matter responses to the use of a nitrification inhibitor: a national series of New Zealand farm trials’ (Carey et al. 2012). We offer the following as a rebuttal and hope this will allay any concerns about the integrity of the data and methodology used in the paper. With respect, Dr Edmeades’ criticism of rising plate meter measurements conflicts with the large body of published peer-reviewed scientific papers that prove that rising plate meters can be used successfully to measure pasture dry matter yield (e.g. Piggot 1989; Thomson et al. 1997; Morton et al. 2005; Gillingham et al. 2007, 2008; Litherland et al. 2008). A study by L’Huillier & Thomson (1988) showed that the rising plate meter reliably and accurately estimated herbage mass of ryegrass/white clover dairy pastures at Ruakura and Taranaki, and Piggot (1989) concluded it was also accurate in Northland. In addition, Lile et al. (2001) conducted a detailed evaluation of the use of rising plate meters on New Zealand dairy farms and concluded that the rising plate meter gives reliable information when using 50 readings per paddock taken in paddocks ranging from 1000 to 4000 kg DM/ha, and appropriate calibrations are used. Dr Edmeades’ criticism of rising plate meter measurements not only conflicts with the published literature but also implies that the results from all previously published peer-reviewed papers that used the rising plate meter are invalid. This cannot be an acceptable conclusion since it would imply that the excellent peer-reviewed published work by renowned scientists such as Piggot (1989), Thomson et al. (1997), Morton et al. (2005) and Gillingham et al. (2008) is now being questioned. Clearly, Dr Edmeades’ criticism of the method of measurement used in the Carey et al. (2012) paper is untenable and should be rejected. Dr Edmeades admits in his letter that his DCD trials were all conducted on either pumice or ash soils (in the North Island). However, the pasture data reported by Carey et al. (2012) includes data from 24 farm trials on sedimentary soils in the South Island. It is unscientific for Dr Edmeades to attempt to dismiss all of the Carey et al. (2012) data based on his own trials (on pumice and ash soil) when it appears that he has not provided any results whatsoever from sedimentary soils. New Zealand Journal of Agricultural Research, 2013 Vol. 56, No. 1, 81 85, http://dx.doi.org/10.1080/00288233.2012.751926

The use of a nitrification inhibitor, such as eco-nTM, to reduce nitrate leaching and nitrous oxide emissions in grazed pastures has become increasingly commonplace, especially on NZ dairy farms. Reducing these types of N losses has a potential benefit to boost dry-matter production but results have varied. We collated pasture response data from a national series of farm trials conducted in 132 paddocks on 37 farms in the North (NI) and South (SI) Islands of New Zealand where paddocks were randomly split into two halves and one half treated with eco-n whilst the other half was not. Measurements were made using pasture plate meters and conformed to a strict protocol. There was a highly significant overall DM response to eco-n use of 19% across all trials (14% NI; 21% SI) although full year responses were more variable between NI regions (427%) than SI regions (12-31%). Generally, DM responses were greater than those demonstrated by previous small-scale experimental trials and this may indicate the influence of a farm-system effect. We speculate several reasons for this effect but further research is required to identify the factors involved.

The use of nitrification inhibitors has become increasingly common on dairy farms in NZ since 2004, ostensibly to reduce nitrogen (N) loss from nitrate leaching and nitrous oxide emissions. A potential benefit of this reduction in N loss, however, is an increase in dry matter (DM) production. Pasture response data were collated from a national series of farm trials conducted in 132 paddocks on 37 farms in the North Island (NI) and South Island (SI) of New Zealand where paddocks were randomly split into two halves with one half treated with the nitrification inhibitor eco-n (TM). Measurements conforming to a strict protocol were made using pasture plate meters. There was a highly significant overall DM response to inhibitor use of 19% across all trials (14% NI, 21% SI) although full-year responses were more variable between NI regions (4-27%) than SI regions (12-31%). Generally, DM responses were greater than those demonstrated by previous small-scale experimental trials and this may indicate the influence of a farm-system effect. Several reasons are speculated for this effect but further research is required to identify the factors involved.

Our project partners include New Zealand Wine, Zespri International, Forestry organisations, Te Rūnanga o Ngāi Tahu and BioGro New Zealand, with linkages also with Dairy New Zealand, Beef + Lamb and Aquaculture New Zealand on the Governance Group.

Field-trial data from a database comprising records of 804 potassium (K) fertiliser trials were used to define the production functions relating exchangeable soil K (quick test K (QTK) 0-75 mm) to the relative response to fertiliser K applications, for the major soil groups in New Zealand. For all soil groups for which there were sufficient data, the production functions were generally flat in the range QTK 5-10, and thus the estimated relative pasture production at QTK 5 and QTK 10 were similar. The critical QTK levels to achieve 97% maximum production were relatively well defined, being 6 (5-8) for sedimentary soils (brown and pallic) and brown soils, and 7 (5-10) for pumice soils. The data for the allophanic soils were unstable and the best estimate was 6 (5-10). For the remaining soils groups (podzols and raw soils, organic, recent and gley soils) for which there was much less data, the relationships were essentially flat over the range QTK 2-10. The probability of pasture responses to applied K increased as soil QTK decreased from 10. For the sedimentary and volcanic soils (including both allophanic and pumice) the probability was about 70-80% at soil QTK < 2. The comparable probabilities were 50-60% for the recent and gley soils, and 30-43% for the podzols and raw soils. A feature of the response functions was that some trials were not responsive to fertiliser K despite having low soil QTK. In most cases this could not be attributed to soil K reserves as measured by the soil TBK test (sodium tetra-phenol-boron extractable which measures exchangeable K plus plant-available but non-exchangeable K). Other possible reasons for this feature in the data are discussed, including uptake of K from below the soil sampling depth and the temporal effects of clover responses to applied K. Soil K buffer capacities-the amount of fertiliser K over and above maintenance required to increase soil QTK by 1 unit (Delta K)-ranged from 50 to > 150 kg K ha(-1) (average 124) for sedimentary soils. For some soils (developed organic soils, gleyed soils and podzols), fertiliser K had very little effect on QTK (0-75 mm). It is not clear whether these differences are due to differences in leaching of K from the sampling depth, differences between soils in their ability to absorb and retain applied K or indeed the result of errors in the measurement of this parameter. Estimated maintenance K requirements (i.e. the amount of applied K required to maintain soil QTK levels) increased with increasing soil QTK from 4 to 10, from 0-150 kg K ha(-1) yr(-1) to 100-300 kg K ha(-1) yr(-1) in situations where losses of K were extreme due to the removal of all harvested clippings. Given the uncertainties in predicting K responses and the amount of fertiliser K required to correct K deficiency, practical suggestions are offered as to how best to diagnose and manage soil K deficiency. Areas for future research to improve the prediction of pasture responses to fertiliser K are also included.