Long Term Soil Fertility Experiments at Oklahoma State University
Variation in Rainfall
Experiment	Location	Focus	Crop	Year Established
222	Stillwater	NPK	wheat	1968
301	Efaw	Municipal wastes	wheat	1993
302	Efaw	Animal wastes	wheat	2000
406	Altus	NPK irrigated	wheat	1965
407	Altus	NPK dryland	wheat	1965
439	Altus	NPK	cotton	1971
501	Lahoma	NPK	sorghum (1970-2004) canola (2005-present)	1970
502	Lahoma	NPK	wheat	1970
503	Lahoma	P Source Method	wheat	1970
504	Lahoma	P Source	wheat	1970
505	Lahoma	N Source	wheat	1970
701	LCB	Zero-Till Topdress	wheat	2001
801	Haskell	NPK	wheat	1977
802	Haskell	P Application	wheat	1977
803	Haskell	K Application	wheat	1977
804	Haskell	Lime Application	wheat	1977
Magruder Plots	Stillwater	NPK-lime	wheat	1892
Mead NE, 1969-1983	Mead, NE	N Rate	corn	1969 (discontinued in 1983)
Articles
Long-Term N Applied