DIVERSE Project Field Experiment Dataset

A field plot experiment was located on the University of Reading farm at Sonning in Berkshire, UK (51°28'21"N -0°54'13"E) and was established in August 2018. Plots were 2 x 11m in size, arranged in a randomised complete block design with 4 blocks/replicates. Each summer, after the harvest of a cereal crop, cover crops were planted and then mowed in the autumn using a lawn mower and either incorporated into the soil of the same plot (Mulch), or removed from the plot (Remove) and added to a plot where cover crops were not grown (Add). Cover crop residues were incorporated by ploughing prior to planting the next autumn sown cereal crop. The cereal rotation was Winter Wheat (2017/18); Winter Barley (2018/19); Winter Oats (2019/20); and Winter Wheat (2020/21). The cover crop treatments were control (no cover crops), buckwheat (Fagopyrum esculentum; variety Hajnalka), berseem clover (Trifolium alexandrinum; variety TIM), oil radish (Raphanus raphanistrum; variety Barracuda), sunflower (Helianthus annuus; variety M6103), and a 4-species mixture of these four. Nitrogen fertiliser was applied at a rate equivalent to 75% of the AHDB RB209 recommended rate for the crop. All other fertiliser and crop protection was applied in line with standard farm practice.

Timeline:
Cover crops drilled on 14th August 2018
Cover crops terminated on 10th October 2018
Barley drilled on 23rd October 2018
Barley harvested on 12th and 15th July 2019
Cover crops drilled on 12th August 2019
Cover crops terminated on 21st October 2019
Oats drilled on 29th October 2019
Oats harvested on 24th August 2020
Cover crops drilled on 1st September 2020
Cover crops terminated on 2nd November 2020
Wheat drilled on 6th November 2020
Wheat harvested on 13th August 2021

Soil samples were taken as a composite sample of three gauge auger cores per plot to a depth of 0-20 cm each summer after cereal crop harvest and before cover crop planting. Soil samples were sieved moist to 4 mm and analysed for soil moisture and available nitrate and ammonium. The remainder of the soil was air dried and sieved to 2 mm and analysed for organic matter, soil pH, Olsen P, and EDTA extractable Cu, Fe, K, Mg, Mn, Na, Ni, S, and Zn. Dry soil was ball milled to a fine powder and analysed for total C and N. Samples (air dried and 2 mm sieved) taken in 2018 only were analysed for soil texture and total (reverse aqua regia digestable) Ca, Cu, Fe, K, Mg, Mn, Na, Ni, P, S, and Zn.

Grain yield was measured using a plot combine and expressed after moisture correction in dry kg per Ha. Grain was milled and analysed for total N, C, Ca, Cu, Fe, K, Mg, Mn, Mo, Na, Mi, P, S, and Zn.
The statistical design of the experiment allows analysis using the following nested ANOVA model: Cover/Treatment/Mixture/Species. Cover has two levels (Yes and No). Treatment has four levels (Mulch, Add, Remove, and Control). Mixture has two levels (Yes and No), and Species has six levels (Control, Buck, Sun, Clover, Radish, and Mix).