Modeling of seedbed creation for spring cereals in clayey soils
Joniškėlis Experimental Station of the Lithuanian Institute of Agriculture,Joniškėlis, LT-39301 Pasvalys District, Lithuania; e-mail: joniskelio_lzi@post.omnitel.net
Abstract:
A model field experiment to establish the optimal parameters of seedbed structure for spring cereals was conducted at the Joniškėlis Experimental Station of the Lithuanian Institute of Agriculture from 2002–2004 on clay loam Gleyic Cambisol.We evaluated seedbed models for spring barley in small plots, where on the top seedbedsublayer (from 0 to 1.5 cm) the portion of desirable large-scale (>5 mm), on the middle sublayer (from 1.5 to 3.0 cm) of medium sized (2–5 mm) and on the bottom sublayer (from 3.0 to 4.5 cm) of smallest (<2 mm) soil structural aggregates made up to 40% in the 1st, 60% in the 2nd, 80% in the 3rd and 100% in the 4th model. Spring barley germination dynamics, emergence and growing intensity on clay loam soil were dependent on the structure of the seedbed and on the moisture content in the topsoil. When the topsoil moisture under the seedbed had decreased to 17.5 and 18.0% the spring barley seeds were germinating more intensively; more seed germinated in the seedbed where desirable soil structural aggregates account for 100 and 80% respectively in all seedbed sublayers, i.e. in the more fractionated seedbed, where bigger soil structural aggregates were taken to the surface, and smaller ones were concentrated deeper, closer to the seeds. When the moisture content in the topsoil was the highest (20.5%), the seedbed structure did not condition a consequent improvement in seed emergence. With increasing the seedbed fractionating, there was increasingly more moisture and higher porosity, less crust forming on the soil surface after rain, and less germination of annual weeds in the spring barley crop.
Key words:
clay loam, seedbed structure, soil physical conditions, spring barley