Long-term monitoring of pasture dry matter production across fields with different pasture types, as assessed by rising plate meter

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This dataset contains estimates of pasture biomass as assessed by a Rising Plate Meter. The data originate from fields on the North Wyke Farm Platform, a national capability in South West England. These fields contained either permanent pasture, a Lolium perenne and Trifolium repens pasture, or a L. perenne only pasture, and all were used as part of a beef and sheep livestock system. Data were collected over 6 years, from April 2018 to March 2024, with either fortnightly (in the summer) or monthly (in the winter) measurements. Multiple measurements were taken per field and per sampling occasion, with the assessor walking in a ‘W’ shaped path across the field. The dataset contains both the individual data points (with latitude and longitude), and the summary for the field per sampling occasion.

The data collection took place on the North Wyke Farm Platform (NWFP), a UK National Bioscience Research Infrastructure in SW England. The NWFP is split into a number of self-contained farms (‘farmlets’) that are managed according to different operation philosophies or practices. The NWFP is highly instrumented and monitored, and core NWFP datasets are open and include in-situ water flow and chemistry taken at 15-minute intervals; 15-minute Met measurements; 15-minute soil moisture measurements; 30-minute GHG emissions; soils, crop and botanical field survey data; livestock and crop performance data; farm operational activities; and contextual information. See the additional information section for further details on how to access these, and for user guides detailing the NWFP design.

The rising plate meter measurements were taken on the NWFP farmlets. The ‘green’ farmlet, with fields of permanent pasture, the ‘blue’ farmlet, where fields were sown with a mixture of high sugar ryegrass (Lolium perenne cv. AberMagic) and white clover (Trifolium repens cv. AberHerald), and the ‘red’ farmlet which was sown with the high sugar ryegrass only. The exceptions were Longlands East (a field on the red farmlet), where the grass was Festulolium (cv. Prior), and Longlands North (a field on the blue farmlet), where the grass was Festulolium (cv. Prior) and the white clover mixture with which the field was oversown in May 2018 was 40% Aberpearl, 40% Aberherald, and 20% Aberace (a wild white clover). The red farmlet was only included until summer 2019, because after this date it was converted to arable. The green and red farmlets received N fertilizer at a standard rate, but the blue farmlet did not due to the inclusion of a legume. Fields within a farmlet are cut for silage and grazed by cattle and sheep, with livestock grazing or consuming silage only from one farmlet.

Pasture height readings were taken with a Jenquip EC20 Bluetooth electronic rising plate meter connected to a smartphone with the Pastureprobe app installed. Readings were taken from every field in the blue and green farmlets on a fortnightly basis in the summer and monthly during the winter, with the change between seasons dictated by pasture growth rates. Multiple readings (minimum 30) were taken per field per sampling occasion, with the assessor walking in a ‘W’ shaped pattern across the field. Wherever possible, rising plate meter readings were taken by the same person to reduce the risk of operator bias, but this has changed over the six year period of the dataset. The Pasture height readings were automatically converted to biomass dry matter within the app using the standard calibration equation: Dry matter (kg/ha) = ((Raw Reading*2)/10) x EquationMultiplier + 500. The raw reading is the number of ‘clicks’ the platemeter is away from the ground when settled on top of the vegetation. Each of the metal divots that act as a click is 0.5 cm high, and therefore the 2 in the equation converts the raw reading to cm, and the divide by 10 is to convert it to mm. The equation multiplier and +500 come from an industry standard formula to produce an average dry matter value. The EquationMultiplier was 125 from April 2018 to 6/4/2023 inclusive. After this date, the EquationMultiplier was 140.

Samples of the pasture herbage (‘snip samples’) were also taken at the same time as the rising plate meter readings in fields that were being grazed. The sample IDs for the snip samples have been included in Summary_data.csv from 2022 onwards in order that users can obtain herbage quality information from the NWFPhttp://resources.rothamsted.ac.uk/farmplatform) to supplement the platemeter readings. Users should download herbage survey data, and match on the GPS_Sample_Nr. Not all of the snip sample data is currently published on the data portal; please email nw.farmplatform@rothamsted.ac.uk if the data you wish to use is not available. There are also snip samples prior to 2022, but the sample IDs have not been included in Summary_data.csv.

Data preparation and processing activities:

Two types of dry matter data have been presented in this dataset. The first type is those with the individual data points taken per field, separated per grazing year. The files are as follows: 2019_2020_NW702.csv, 2020_2021_NW735.csv, 2021_2022_NW752.csv, 2022_2023_NW769.csv, 2023_2024_NW785.csv. Users should be aware that some latitude and longitude values are missing and have not been gap-filled. There are also some fields and sampling occasions when the latitude and longitude is not unique for each reading in the W, but data have been presented as we have it. Also note that the first two years of collecting individual data points from fields (2019_2020_NW702.csv and 2020_2021_NW735.csv), this was only done in the green farmlet. There are no individual datapoints for the red farmlet.

The second type of data are the summary data (Summary_data.csv). These data cover the period 2019-2024 and provide a single dry matter value for each field per sampling occasion. Notes on provenance: the dry matter values are typically the average value provided by the Jenway pasture app. Comparing the values to the mean of the individual datapoints, as contained in the csv files reference above, values are typically very similar, but not necessarily identical. Partly this is because it is unclear how the Jenway pasture app rounds the values to replicate it in the values from the individual datapoints; in some places it appears to be to the closest 25, other times the rounding number must be smaller. In a small number of cases, the discrepancy between the two data types is larger. The Summary_data.csv contains the average value provided by the Jenway pasture app, rather than the arithmetic mean from the individual datapoints, where both methods produce a dry matter value. This is for 2 reasons: 1) users can calculate the arithmetic mean from the individual datapoints if they wish, and 2) there are many occasions (2018-2019, 2019-2020 for the red and blue farmlets, occasional other measurements in the later years) where there is a summary value provided by the Jenway pasture app but no individual datapoints. However, there were some occasions where there were individual datapoints, but no average dry matter calculated by the Jenway pasture app. In this case, the arithmetic mean has been provided in Summary_data.csv instead. If users wish to distinguish between the two, they can use the column ‘Source’. If the Source is 1, the dry matter value originated from the Jenway pasture app, and if the source is >1, the dry matter value is a mean of the individual datapoints for that field and sampling date.

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