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Variable efficacy of the acetohydroxyacid synthase (AHAS) inhibitor herbicide, flumetsulam, against dairy pasture populations of Ranunculus acris, has been attributed to resistance. We compared, over two years, the fitness of two resistant (R) clones and nine susceptible (S) clones treated or not with flumetsulam by measuring seed yields and survival of plants. Without the herbicide, all plants grew and survived. The seed yields of the R and S plants without the herbicide were similar (327 and 217 seeds/plant, respectively in Year 1, and 257 and 323 seeds/plant in Year 2) indicating no fitness penalty to the resistance. With the herbicide, growth and survival of the R plants was unaffected, whereas all S plants were defoliated before seedhead formation but 96% regrew from their rhizomes in Year 2. Seed yields of the treated R and S plants in Year 1 were 347 and 0 seeds/plant, respectively and 243 and 205 seeds/plant in Year 2. Survival of flumetsulam-susceptible R. acris plants following spraying would maintain susceptible AHAS alleles in the population, while without a fitness penalty, resistant plants would persist in non-spraying years facilitating further selection when the herbicide is used again. [ABSTRACT FROM AUTHOR]

Reliable data on the rate of cadmium (Cd) accumulation in soils that receive phosphorus (P) fertiliser is vital to help manage the impact of Cd in agricultural systems in New Zealand. Studies of the long-term P fertiliser trial at Winchmore, where soils have received 0, 17, or 34 kg P ha−1 yr−1 for > 60 years, have reported that soil Cd concentrations over the last 15 years have either plateaued or are still increasing. To address this discrepancy, new soil Cd analysis was conducted on a wider set of archived soil samples from the Winchmore trial, along with some re-analysis of soil samples for Cd. When soil Cd data from previous studies were combined with the more recent set of Cd data, regression analysis indicated soil Cd concentrations in the 17, or 34 kg P ha−1 yr−1 fertiliser treatments are still increasing linearly over time. It is recommended soil samples from the long-term Winchmore trial continue to be analysed for Cd to confirm long-term trends, avoiding short-term perturbations. Such long-term trials are invaluable for providing robust information that will help in the ongoing management of Cd in New Zealand. [ABSTRACT FROM AUTHOR]

The efficacy of control tactics for Ranunculus acris was quantified on poorly- and well-drained soils in a factorial experiment conducted over three years in 18 dairy pastures. Soil drainage, gibberellic acid and nitrogenous fertiliser (growth promoters), and a bioherbicide utilising Sclerotinia sclerotiorum had no effect on the cover of R. acris. The herbicides aminopyralid and aminopyralid+triclopyr, by contrast, gave long-lasting reductions in the cover of the weed and substantial temporary reductions in the clovers. Flumetsulam, thifensulfuron methyl, MCPA, MCPB and MCPB+bentazone were less effective overall. Pregraze mowing reduced R. acris as the frequency of mowing increased. For all herbicides, there was a 1:1 replacement of R. acris by grasses and clovers. The efficacy of the treatments varied greatly between pastures, possibly due to genetic differences between the R. acris populations and their historical exposure to the herbicides. [ABSTRACT FROM AUTHOR]

Drought reduces pasture production. Irrigation can be an effective response in such situations, but if we apply too little water, production will be less than in the well-watered potential. If we apply too much, nutrients can be leached, reducing soil fertility and causing environmental concern. To evaluate uniformity of water application, we developed a graphical method to analyse measurements along linear transects. By plotting the data, variable results were readily identified as well as potentially systematic patterns. The plot was divided into quadrants and the observations in each quadrant counted. For a random spatial distribution, one-quarter were expected in each quadrant. The observed and expected counts were compared using a Chi square statistical test. To illustrate, we analysed measurements from eleven irrigated farms and data representing contrasting hypothetical situations. The results were informative and appropriately responsive. Using a picture to classify and count the data can be an intuitive, practical method to evaluate an irrigator’s performance [ABSTRACT FROM PUBLISHER]

Static chambers are often used for measuring nitrous oxide (N 2 O) fluxes from soils, but statistical analysis of chamber data is challenged by the inherently heterogeneous nature of N 2 O fluxes. Because N 2 O chamber measurements are commonly used to assess N 2 O mitigation strategies or to determine country-specific emission factors (EFs) for calculating national greenhouse gas inventories, it is important that statistical analysis of the data is sound and that EFs are robustly estimated. This paper is one of a series of articles that provide guidance on different aspects of N 2 O chamber methodologies. Here, we discuss the challenges associated with statistical analysis of heterogeneous data, by summarizing statistical approaches used in recent publications and providing guidance on assessing normality and options for transforming data that follow a non-normal distribution. We also recommend minimum requirements for reporting of experimental and metadata of N 2 O studies to ensure that the robustness of the results can be reliably evaluated. This includes detailed information on the experimental site, methodology and measurement procedures, gas analysis, data and statistical analyses, and approaches to generate EFs, as well as results of ancillary measurements. The reliability, robustness, and comparability of soil N 2 O emissions data will be improved through (a) application, and reporting, of more rigorous methodological standards by researchers and (b) greater vigilance by reviewers and scientific editors to ensure that all necessary information is reported in scientific publications., (© 2020 The Authors. Journal of Environmental Quality published by Wiley Periodicals, Inc. on behalf of American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America.)