Study of Tillage Systems Effect and Number of Weeding on Species of Weeds and Yield of Corn

Constraints to effective weed management may be the main reason for the small area under minimum tillage (MT) in smallholder farming in Iran. The effect of tillage systems and intensity of hand hoe weeding on the growth of weeds and maize (SKC 108) was investigated in the 2013–2014 growing season a field experiment at Tehran Research Station (28830.920E, 20823.320S). The experiment was a split-plot randomized complete block design with four replications. Tillage was the main plot factor (conventional tillage – mouldboard tillage (MBT) compared against minimum tillage (MT) – disc) and hoe weeding rate the sub-plot factor. Hoe weeding was done either two times (high weeding intensity), one (low weeding intensity) and no weeding during the cropping season. There was markedly greater early season weed growth in minimum tillage (MT) relative to mouldboard tillage (MBT) in crop season. MT tillage system had higher weed biomass (285.26 g/m^2) measured than MBT (278.63 g/m^2) system. The high weeding intensity treatment had lower weed growth and better maize yield than high weeding intensity. MBT had the higher maize ear length, 1000 grain weight, maize total dry weight, harvest index, total maize N uptake, grain N uptake and grain N concentration which translated significantly higher than in MT system. Maize grain yield obtained from MT system was less than (4.250 t/ha^1) compared to (4.931 t/ha^1) in MBT. Results suggest that MT systems require early and frequent hoe weeding even many years to reduce weed infestations and improve crop growth. This higher demand on a smallholder household’s limited labor supply throughout the cropping season will be a key determinant of the spread and adoption of MT systems in Iran.