Fallow replacement using indianhead lentils: water use, yield and oil nitrogen

Pikul Jr, J.L. and Aase, J.K. and Cochran, V.L. (1996) Fallow replacement using indianhead lentils: water use, yield and oil nitrogen. pp. 183-190. In: Proc. of the Great Plains Soil Fertility Conf., Vol. 6. USA-CO-Denver, 1996/03/04-06.

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Abstract

Because of increased costs of fertilizer and evidence of declining soil quality there has been
renewed interest in crop rotations using legumes in the traditional spring wheat-fallow rotation
areas of the semiarid northern Great Plains. Objectives were to test a "green fallow" method of
farming as a system to build soil nitrogen and efficiently use water. We compared mechanical
fallow using sweeps (N1F) and chemical fallow (CF) to green fallow. Fallow treatments MF and
CF received 30 lb-N/acre. as N1-14NO3 broadcast prior to seeding wheat (Triticum aestivum L.).
Lentils (Lens culinaris Medikus, cv. `Indianhead') were grown as a green manure crop in a green
fallow-spring wheat rotation. The experiment was started in 1991 as a randomized complete block
with four replications and MF as control. Soil was a Williams loam ( fine-loamy, mixed Typic
Argiboroll) 7 miles north of Culbertson Montana. At full bloom, lentils were either killed by
disking (GMMF) or chemical burn-down (GMCF). Average dry-weight of Indianhead lentils for
1991, 1992, and 1993 was 1500 lb/acre compared to an average of 4700 lb/acre for 1994 and 1995.
Average water use by lentils in 1991, 1992, and 1993 was 10.6 inches. In contrast, MF and CF lost
9.9 inches. Average water use by lentils in 1994 and 1995 was 12.9 inches which was significantly
more than the loss of 10.7 inches on MF and CF. At spring planting, there were no differences in
soil water content among treatments. Wheat yield was 25% less on green fallow compared to MF
and CF. Soil NO3 -N levels were 35 % lower on green fallow rotations than MF and CF rotations.
There were no differences among treatments in nitrogen mineralization rates in 1993 following two
cycles of green manure. Lack of available nitrogen, rather than lack of soil water, appears to have
restricted wheat production on green fallow treatments.

Item Type:	Conference or Workshop Item (Paper)
NWISRL Publication Number:	0901
Subjects:	Irrigated crops > Bean / dry bean Mass Import - autoclassified (may be erroneous)
Depositing User:	Dan Stieneke
Date Deposited:	20 Nov 2010 21:57
Last Modified:	10 Nov 2016 16:11
Item ID:	1078
URI:	https://eprints.nwisrl.ars.usda.gov/id/eprint/1078