Phosphorus in Agriculture: A Review of Results from 175 Years of Research at Rothamsted, UK

Abstract

Insight into the role of phosphorus (P) in soil fertility and crop nutrition at Rothamsted, UK, and its involvement in associated environmental issues, has come from long‐term field experiments initially started by J. B. Lawes in 1843 and continued by others, together with experiments on different soils. Results from the 1940s confirmed that residues of P applied in fertilizers and manures build up reserves of P in soil. There is a strong relationship between crop yield and plant‐available P (Olsen P), and a critical level of Olsen P can be determined. For soils near the critical level, P‐use efficiency is high when the P applied and offtake by the crop is nearly equal. Soil inorganic P is associated with various soil components and is held there with a range of bonding energies so that when no P is applied, the decline in Olsen P follows a smooth curve. We conceptualize inorganic soil P as being in four pools of vastly varying size, availability for uptake, and extractability by reagents used in routine soil analysis, and with reversible transfer of P between pools. For very disparate soils at Rothamsted and in the United States, there is a strong relationship between the change in Olsen P and P removal/input ratios, suggesting an underlying similarity in inorganic P behavior. Maintaining soil near the critical level should optimize yield and the use of the global P resource while minimizing the risk of transfer of large amounts of P to the aquatic environment. Core Ideas Lawes started long‐term experiments on P in the 1840s. Insights into role of P in soil fertility and crop growth comes from field experiments. P residues build up a reserve of plant‐available P. Olsen's method is used to establish critical level of available P in soil for optimum yield. Inorganic P transfers between 4 pools of different size/extractability/availability.

The importance of long‐term experiments in agriculture: their management to ensure continued crop production and soil fertility; the Rothamsted experience

“…In 1964, the plots had been divided further to establish four levels of Olsen P and four levels of exchangeable K, as on the Exhaustion Land (see below), with the unique opportunity to do this at two levels of SOM in this one experiment after growing grass for 12 years. The critical level of plant‐available Olsen P for three arable crops at two levels of SOM is shown in Table (Johnston & Poulton, ). By 1973, successive modifications had resulted in each of the six original large plots (each 24 m × 58 m) being divided into 64 sub‐plots (each 6 m × 6 m).…”

Increasing the Effectiveness and Adoption of Agricultural Phosphorus Management Strategies to Minimize Water Quality Impairment

“…Sharpley et al (2013) calculated drawdown times ranging from 4 to 27 yr on a range of soils from the United States, Canada, and Europe. Ultimately, many high‐STP soils can be farmed with no or limited P additions without affecting yields for decades, but during P drawdown, these soils will continue to lose P to water resources (Qin and Shober, 2018; Johnston and Poulton, 2019). …”

Phosphorus mirabilis: Illuminating the Past and Future of Phosphorus Stewardship

“…The earliest documented cause‐and‐effect research on the use of P as a fertilizer in crop production was conducted at Rothamsted Research (previously known as Rothamsted Experimental Station and the Institute of Arable Crops Research), located in Harpenden, UK, founded in 1843, making it one of the oldest agricultural research institutions in the world (https://www.rothamsted.ac.uk/about). Johnston and Poulton (2019) demonstrate how 175 years of field experiments at Rothamsted provide a unique insight into the role of P in soil fertility and crop growth, as well as the build‐up and drawdown of plant‐available P. The “Park Grass Experiment” initiated in 1856, remains one of the longest continuously monitored soil fertility studies. Johnston and Poulton (2019) highlight how the collaboration between John Lawes (an entrepreneur, scientist, and founder of Rothamsted Experimental Station) and Joseph Gilbert (a chemist) during the last half of the 19th century forged an interdisciplinary alliance that has served as a model, both then and now, for how collaborative research can transform agricultural production systems.…”

“…Given the complex and interdependent influences of climate, land management, and soil type, it is clear that improving PUE will be site specific to a large degree. The unique historical dataset for Rothamsted Research documents strong relationships between crop yield and Olsen soil test P that facilitate identification of “critical levels” of Olsen P for optimizing PUE (Johnston and Poulton, 2019). However, Hopkins and Hansen (2019) remind us that high‐yield cropping systems require both high P supply and high P uptake; therefore, the “critical” soil test P levels may be too low for intensively managed scenarios.…”