In the tropical soil environment, raindrop impact is capable of disrupting natural soil aggregation and porosity, thus influencing the amount of infiltrated water and its redistribution. Under such conditions, a vegetation cover of weeds cannot be viewed simply as a crop competitor. This research project was designed to examine, under field conditions, the changes of soil properties, namely soil water content, structure and sealing, resulting from different types of weed management, with the aim of contributing to the establishment of more sustainable agricultural practices. Four weed management types - hoe-weeded, bare soil (combined application of pre-emergence herbicide Arsenal-250® (Imazapir) 2.0 L ha-1 and the systemic herbicide Gliz® (Glifosate) 5.0 L ha-1), cut and cut + herbicide (systemic herbicide Gliz®(Glifosate) 5.0 L ha-1) - were studied on an intensively cropped Kanhapludult in Minas Gerais State, Brazil. In high rainfall periods, the insulating effect of cut and cut + herbicide resulted in higher soil water, as compared to bare soil and hoe-weeded. On the other hand, in dry periods, the bare soil and hoe-weeded covers presented higher soil water content than the cut and cut + herbicide. Based on macro and micropedological observations, a sealing effect up to 15 mm below the surface was observed in bare soil and hoe-weeded covers and was particularly well-sorted and stratified in the latter. It is postulated that microerosional and microdepositional processes are involved in hoe-weeded sealing. These processes result from the breakdown of microaggregates, repacking the soil matrix. In the bare soil, the sealing was associated with physical alterations in the top layer, related to raindrop impact. Cut and cut + herbicide covers showed greater development of algae, bryophytes and worm activity in the soil surface. Based on the results obtained, the use of motorized cutters associated with herbicides appears to be a suitable alternative to hoeing and hand-weeding, reducing soil physical degradation and losses of water and soil in this particular environment.
Land use; sealing; micropedology; ultisol; soil water content; weed control