Prepared summaries of commonly requested data from the long term experiments at Rothamsted Research are being made openly accessible to the scientific community. We hope greater use of the data by the global research community will lead to further understanding and wider benefits. We welcome any feedback on this. Please contact the e-RA curators for further information.
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Mean long-term winter wheat yields from selected treatments on Broadbalk are shown. The changes reflect the improved cultivars, cultivations and control of pests, diseases and weeds that have been introduced on Broadbalk, especially since the 1960s. Yields of continuous wheat given no fertilizer or manure have remained at around 1 t ha -1. Since 1979 summer fungicides have been used, which has allowed us to exploit the greater grain yield potential of modern cultivars. In 1968 a rotation was introduced on part of the experiment, so that it is now possible to compare the yields of wheat grown continuously and as the first wheat after a two year break. The highest yields are now from the first wheat crop in rotation, with the best yields from fertilizer alone exceeding those from FYM alone, and the combination of FYM + 96 kgN ha-1 (144 kgN ha-1 since 2005) often exceeding both.
Changes in soil organic carbon (SOC) content in selected treatments of the Broadbalk experiment, where winter wheat has been grown each year since autumn 1843. SOC (0-23cm) has remained almost constant in the unfertilized plot, at the equilibrium level for this farming system on this soil type. Inorganic fertilizer (NPK) has enhanced SOC a little, probably due to increased returns of organic matter in crop roots and residues. The treatment given 35 t ha-1 FYM now contains almost three times as much SOC as the unfertilized plot. Increases were greatest in the initial years of the experiment.
Changes in plant-available P (Olsen P) in the topsoil (0-23cm) of selected plots of the Broadbalk wheat experiment since 1843. The accumulation of available P was greatest on the FYM plot, reflecting the larger total P inputs in FYM compared to that applied as inorganic fertilizer or where no P was applied. The larger Olsen P concentrations on plot 5 (PKMg) compared to plot 8 (N3PKMg), despite their similar P inputs, were a result of the higher yields and greater P offtakes in the crop on plot 8, due to the applied N. The relatively low Olsen P concentrations on plot 18 (N2 1/2PKMg) were a result of the limited P inputs between 1844 and 2001. Olsen P concentrations were least on plots receiving no (or very little) P inputs in fertilizer (plot 3, given no fertilizer or manure).
The accumulation of organic carbon in soil and tree biomass has been measured on two contrasting sites at Rothamsted that were fenced off in the 1880s and allowed to revert naturally to woodland. Both sites had grown arable crops for many years before. Although not experiments in the usual sense, these two areas of regenerating woodland are of great value, providing information on the long-term sequestration of carbon in soil and vegetation.
The larger Geescroft site grew beans (Vicia faba) for many years, and has been left uncultivated since 1883. It did not recieve as much chalk as the Broadbalk site, and the soil is now acidic (pH 4.4 in 1999).