Exhaustion Land

Description

• Four plots were established on the Exhaustion Land site in 1856, this was known as 'Smith's Wheat' experiment. Winter wheat was grown each year. In 1876 the four plots were divided and two more plots were added, from a strip of unmanured and unfertilized wheat on the north side of the experiment. This was known as the 'Potato experiment', and potatoes were grown every year from 1876-1901. From 1856 to 1901, the plots received annual applications of N, P, K or FYM. There were 10 plots from 1876 to 1901, each 0.067 ha (1/6th of an acre).

Design

• Period: 1856 - 1901
• Experiment Design Type: Demonstration strip design

Crops

Factors

Factor Combinations

Description

• Between 1902 and 1939 no fertilizers or manures were applied and, with a few exceptions, cereals (usually spring barley) were grown. The site was fallow in 1920. Yields were recorded in some of the earlier years, and residual effects of the previous treatments were very small in the absence of fresh nitrogen fertilizer. Yields were not recorded from 1923-1939, except in 1935.

Design

• Period: 1902 - 1939
• Number of Plots: 10

Description

• Between 1940 and 1985, spring barley was grown and N fertilizer applied to all plots every year. Initially a single rate was applied, 63-88 kg N/ha. In 1976 the 10 main plots were each divided to test four rates of N (0, 48, 96 and 144 kg N/ha), which were rotated each year. No other fertilizer or manure was applied 1902-1985. No crop was grown in 1967 or 1975. Grain and straw yields were recorded from 1949 onwards. Nitrogen not only increased yields, but allowed the crop to take advantage of P and K residues remaining in the soil from Phase I of the experiment. The effects of these were initially large but declined as amounts of phosphate in the soil declined.

Design

• Period: 1940 - 1985
• Number of Plots: 10
• Number of Sub-plots:
• Number of Harvests per Year: 1

Crops

Factors

Description

• In 1986, after a long period when the P residues in particular were being “exhausted”, it was decided to see how quickly this decline in soil fertility could be reversed. Annual, cumulative dressings of 0 v 44 v 87 v 131 kg P ha-1, as triple superphosphate, were tested on five of the original plots (each divided into four sub-plots). Spring barley was grown. This was known as the "P Test". Basal N and K were applied such that these nutrients did not limit yield. Responses to fresh P were rapid. Applications of P stopped after seven years. No P was applied between 1993 and 1999, but since 2000, maintenance dressings, equivalent to offtakes by the crop, have been applied (not to the no-fresh-P sub-plots). Wheat has been grown since 1992. Typically, it showed the same response to available-P as spring barley i.e. above a critical level, on this soil, of about 12 mg kg-1 there is no further increase in yield.

Design

• Period: 1986 - 2006

Crops

Factors

Description

• On the other half of the experiment, the effects of K residues (in the presence of basal P and N) on yield are investigated (the "K Test" plots). Since 2007, annual cumulative applications of 0, 62.2 and 124.5 kg K ha-1 as muriate of potash have been applied (K0, K1 and K2). Basal N and P has been applied so that yields are not limited. From autumn 2015 P was withheld from plots 013, 033, 053, 073 and 093 ("P Test" plots) in addition to those which no longer receive P (plots 014, 034, 054, 074 and 094) because the plant available P was increasing on these plots. See Exhaustion Land today for more details.

Design

• Period: 2007 - Now