6 31 PCentra' e ,ce
P Library
7/-o0 NOV 13 1991
 Agronomy Research Report AY-91-06

 Growth and Nitrogen Content of Tift Blue lie of Florida

 Raymond N. Gallaher
 Professor of Agronomy, Agronomy Department, Inst. Food and Agr.
 Sci., University of Florida, Gainesville, FL 32611

 ABSTRACT

 The use of lupine (Lupinus ancustifolius L.) as a cover crop,
 in succession double cropping, may be one solution in the quest for
 sustainable agricultural production systems. The objective was to
 determine distribution of dry matter and N in the life cycle of
 'Tift Blue' lupine at 25, 50 and 100 plants m-2. Lupine planted 9
 November 1990 at 25, 50 and 100 plants m-2 were grown on an
 Arredondo sand (Grossarenic Paleudult). Plants including roots to
 0.45 m soil depth were collected eight times from 1 m2 plots from
 27 to 171 days after planting (DAP). After washing, the samples
 were separated into plant parts, dried, weighed, ground and
 analyzed for N. Dry matter and N accumulation patterns were
 similar for the 50 and 100 plants m2, and both accumulated about
 twice as much dry matter and N as the 25 plants m'2. Highest dry
 matter and N content for the 100 plants m'2 were 2134 and
 35.96 g m"2, respectively at 147 DAP.

 INTRODUCTION

 Winter legumes are used for cover crops, protein sources,
 mulches for succeeding no-tillage crops, rotations for pest
 management and for improving soil fertility. When grown as a cover
 crop, lupine (Lupinus anqustifolius L.) can be sacrificed for the
 N and conservation benefits of the succeeding double crops such as
 corn (Zea mays L.) or grain sorghum (Sorghum bicolor L. Moench)
 (Gallaher and Eylands, 1985). Such a cover crop can serve as a
 mulch to conserve soil moisture if the soil has moisture to
 conserve (Gallaher, 1977). A mulch will aid in reducing erosion,
 moderate soil temperature, aid in competition against weed growth
 and conserve soil moisture from natural rainfall or irrigation. It
 may also furnish N and other recycled nutrients (Gallaher, 1986)
 and in some rotations may also be useful in controlling pests, such
 as breaking the cycle of nematodes, etc. Cover crops can be killed
 before or after the succeeding multiple crop is planted using no-
 tillage management (Gallaher, 1980). The objective was to
 determine distribution of dry matter and N in the life cycle of
 'Tift Blue' lupine at 25, 50 and 100 plants m2.