JWSS - Journal of Water and Soil Science

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Knowledge of the effects of row spacings and seeding rates on dual-purpose forage and seed production of an annual legume crop is essential for its proper agronomical exploitation. In this study, the effects of various row spacings and seeding rates on dry matter and seed yield in berseem clover (Trifolium alexandrinum L.) were evaluated in two consecutive years. The experimental design was a split-plot with four row spacings as main plot treatments in a randomized complete block design with four replications, and five seeding rates were allocated to subplots.

Combined analysis of variance of the two-year data showed that both row spacings and seeding rates influenced dry matter yield (DM), seed yield, plant height, 1000-seed weight and harvest index. Years, as well as two- and three-factor interactions did not affect the seed yield whereas row spacing × seeding rate, and year × seeding rate significantly affected the DM. The mean comparisons indicated that row spacings of 30 and 45 cm produced the highest DM of 3912.2 and 3900 kg/ha 45 and 60 cm spacings showed the highest seed yield of 1045.4 and 1093.3 kg/ha, respectively. 24 and 20 kg/ha seeding rates ranked the best in giving 1244.7 and 1223 kg/ha seed yield, respectively. The seeding rate of 16 kg/ha in the first year and 20 kg/ha in the second year produced the highest DM yield with means of 3837.5 and 3875.3 kg/ha, respectively. Regarding the dual-purpose of forage and seed production in berseem clover, 20 kg/ha seeding rate at 45 cm row spacing can be recommended for Isfahan region and for other comparable environmental conditions.

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Effects of five various tillage systems on soil porosity, volumetric water content, diurnal and nocturnal soil temperatures, plant water uptake and dry matter yield was investigated using a completely randomized design with five treatments and four replications in Gorgan University of Agricultural Sciences and Natural Resources research farm located in Seyed-Miran during 2009-2010 growing season. Tillage systems were: moldboard plough followed by one discing (20-25 cm) rototiller (12-17 cm) double disc (8-10 cm) Chisel plow (25-30 cm) No-tillage. Results show that during all stages of wheat growth, the highest and the lowest soil porosities at 0-8 cm depth were obtained by moldboard plough and No-tillage treatments respectively. For all stages except before tillering and harvest, the highest soil porosity obtained by moldboard treatment at 8-16 cm depth. Increasing tillage intensity increased those porosity that keep water in potentials greater than -5 and those in potentials less than -15 bar. No-tillage and moldboard induced the highest and the lowest soil temperatures respectively before earring stage. Tillage intensification, increased soil porosity and root density. More roots reduced soil water content in response to increased water uptake by wheat, resulting greater dry matter accumulation.