Effect of Different Seed Rates on Yield and Some Agronomic Traits of Alfalfa Mohageran Ecotype in no-till and conventional tillage Methods in Semirom Region

In agriculture section, more than half of the consumption energy is used for tillage. No-till systems can provide optimal conditions for some crops production because of less energy usage, optimal watering, and physical regime for plant and optimal microbial activities for humus synthesis. Although the climate change and the drought in recent years have restricted alfalfa cultivated area, it still provides about 40% of animal feed within 35 million hectares. Alfalfa with 20% protein is the first forage in the world.

In order to compare alfalfa cultivation in no-till and tillage methods with different rate of seeding, an experiment was carried out as RCBD in the form of a strip split plot plan, during 2013-2015 in Semiroum region, Esfahan province, Iran. The main strip plot (horizontal) was cultivation methods including no-till and conventional tillage methods, and strip subplot (vertical) was the four rate of alfalfa seeding including 10, 20, 30, and 40 kg/ha. The cutting time of alfalfa was the time factor in treatments. The planting operation was carried out after harvesting of barley cereals with 30% residual straw in the mid-summer. The measurable parameters in different treatment included the number of established plants in the first spring, fresh and dry forage yield divided different cuts, stem density divided different cuts, and the numbers and weight of weed.

Variance analysis showed that there is no significant difference between no-till and conventional tillage methods in terms of fresh and dry forage production. The seeding rate as a sub-factor has significant effect (level 1%) on fresh and dry forage and number of stem per unit area, whereas the interaction effect between cultivation methods with seeding rate has not significant effect on forage production and number of stem per unit area. The plant density, and the number of weeds were affected from cultivation methods (conventional tillage and no-till), whereas the plant density and number of weeds in no-till method was superior to tillage system. The plant density was varied between different of seeding rate, whereas the number of weed has not affected from the seeding rate.

The obtained results indicated that regarding the alfalfa cultivation in no-till method (with 30% residual straw), not only the forage production was equal to conventional tillage method, but also the number of plant in no-till method was higher than tillage method. It seems that the superiority of no-till method in plant referred to proper seed placement because of minimum plough of soil in no-till method. However, the number of weed in no-till method was higher than conventional tillage method, but this item had no effect on the yield and stability of alfalfa, because the presence of weeds was only related to the first cutting. Using the no-till cultivation method with 30 kg of seeding rate per hectare produced 60.76 ton/ha fresh forage and 10.77 ton/ha dry forage.