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United States Department of Agriculture

Agricultural Research Service

Title: Lentil Water-Use and Fallow Water-Loss Comparisons in a Semiarid Climate

Authors
item Aase, J
item Pikul Jr, Joseph
item Prueger, John
item Hatfield, Jerry

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 10, 1996
Publication Date: N/A

Interpretive Summary: There has been a resurgence of interest in legumes for green manures, or as partial summer fallow replacement-crops. Therefore it is important to know water requirements of legumes in semiarid agriculture. Our objective was to evaluate seasonal water use by black lentil and to relate water use to plant responses useful as soil water management tools. The study was conducted 7 miles northwest of Sidney, Montana during 1993 and 1994 in a typical strip-crop environment of the semiarid northern Great Plains. Plant height was related to growing degree days (GDD) (a sum of mean daily temperatures) with the same relationship for both years. Cumulative evapotranspiration (ET) was related to GDD for both years until about 800 GDD, corresponding to nearly 12 inches of ET. It becomes a matter of judgement and rainfall probabilities to determine how much soil water to sacrifice with hopes of water recovery during the non-crop period, for use by a following commercial crop. At full bloom, equivalent to near 1800 lbs/acre dry matter production in both years, lentils used about 2 to 2.8 inches more water than fallow. Probably no more than 2 inches above that lost to fallow should be sacrificed if a grain crop is to be seeded the following year. From a practical standpoint, because plant height was closely related to both GDD and cumulative ET, it appears like a simple measure of lentil height can give sufficient accuracy for deciding when lentil as partial summer fallow replacement-crop should be terminated.

Technical Abstract: With a resurgence of interest in legumes for green manures, or as partial summer fallow replacement-crops, it is important to know water requirements of these crops in semiarid agriculture. Our objective was to evaluate seasonal water use by black lentil (Lens culinaris Medikus), a potential fallow replacement crop, and to relate water use to parameters useful as soil water management tools. Two precision weighing lysimeters, on a Williams loam near Sidney, MT, were located in a typical strip-crop environment of the semiarid northern Great Plains. Lentil was seeded no-till into wheat (Triticum aestivum L) stubble on one lysimeter field in 1993, the other was left in chemical fallow. Seeded and fallow fields were rotated in 1994. Plant height vs. growing degree days (GDD) was the same for both years. Cumulative evapotranspiration (ET) was related to GDD for both years until about 800 GDD, corresponding to nearly 300 mm ET. It becomes a matter of judgement and rainfall probabilities to determine how much water to sacrifice with hopes of water recovery during the non-crop period, for use by a following commercial crop. At full bloom, equivalent to near 2 Mg/ha dry matter production in both years, lentils used about 50 to 70 mm more water than fallow. Probably no more than 50 mm above that lost to fallow should be sacrificed if a grain crop is to be seeded the following year. From a practical standpoint, because plant height was closely related to both GDD and cumulative ET, it seems plausible that a simple measure of lentil height can give sufficient accuracy for determining when lentil as a partial summer fallow replacement-crop should be terminated.

Last Modified: 10/23/2014
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