Mechan­i­cal weed con­trol methods 

Mechan­i­cal weed con­trol and stub­ble cul­ti­va­tion meth­ods can be used even before a crop is actu­al­ly sown. Ploughs and cul­ti­va­tors are both good options for large-scale cul­ti­va­tion. Weed removal is absolute­ly crit­i­cal for cre­at­ing opti­mum con­di­tions for the main crop and ensur­ing good yields. Nev­er­the­less, mis­takes can be made dur­ing seedbed prepa­ra­tion that encour­age weed infes­ta­tion and require addi­tion­al mea­sures to be tak­en. Over the past cen­tu­ry, more and more chem­i­cal alter­na­tives have been used in addi­tion to the var­i­ous mechan­i­cal meth­ods of weed con­trol. Chem­i­cal plant pro­tec­tion prod­ucts became wide­ly accept­ed because they are easy and cheap to apply. They have, how­ev­er, come under increas­ing crit­i­cism, which has led to a search for alter­na­tives. Apply­ing plant pro­tec­tion prod­ucts incor­rect­ly or too often can also cause weed resis­tance, which makes it dif­fi­cult to con­trol weeds. What is more, mechan­i­cal weed con­trol seems to be the only option for organ­ic farm­ing and veg­etable cul­ti­va­tion due to the require­ments that exist in this sec­tor. Fre­quent plough­ing has a neg­a­tive impact on the soil struc­ture, which is why using water-sav­ing min-till meth­ods makes sense. Dis­ad­van­tage: it can lead to increased weed infes­ta­tion in the field. The large-scale mechan­i­cal cul­ti­va­tion of arable land is rel­a­tive­ly sim­ple before sow­ing, but becomes hard­er once the main crop has ger­mi­nat­ed. This is because greater pre­ci­sion is required after sow­ing and crop emer­gence com­pared to dur­ing the seedbed prepa­ra­tion stage. There are var­i­ous ways to approach this and we will cov­er them in the next section.

Hoe­ing and harrowing 

There are three sce­nar­ios for mechan­i­cal weed con­trol once the main crop has ger­mi­nat­ed: between the rows, in the rows and on the surface.
Hoes and ploughs work between the crop rows. Ploughs are used to form ridges and should cov­er unwant­ed weeds in the rows with soil in order to hin­der their growth. This approach is often seen in maize pro­duc­tion. Hoe­ing imple­ments, on the oth­er hand, remove the weeds from the soil in between the rows. The uproot­ed plants lying on the sur­face dry out in the warm weath­er and die off. For good results, the hoe­ing ele­ments must run close­ly along­side the plants of the main crop. With­out auto­mat­ic guid­ance, you need to have a clear view of the blades. Oth­er­wise, it is impos­si­ble to guide the vehi­cle precisely.
Spe­cial tools such as tor­sion weed­ers can be used to con­trol weeds mechan­i­cal­ly with­in the rows. These con­sist of spring tines that move with­in the rows. The tines are deflect­ed from the main crop and only remove unwant­ed growth from between the plants. As such, this method of mechan­i­cal weed con­trol can only be used on sta­ble, estab­lished crops. Fin­ger weed­ers, on the oth­er hand, work in a sim­i­lar way to a disc har­row; the main dif­fer­ence being that they con­sist of mul­ti­ple indi­vid­ual fin­gers that press into the soil between the plants and uproot and remove the weeds.
Har­rows are more suit­ed to large-scale weed con­trol.. They often con­sist of mul­ti­ple indi­vid­ual spring tines that are dragged over the crop. When used cor­rect­ly, the estab­lished plants from the main crop are not dam­aged in the process and remain in the ground. Weeds, on the oth­er hand, are uproot­ed and removed. Pos­i­tive side effect: it encour­ages tiller­ing in cere­al crops. When har­row­ing, the soil should be loose and free flow­ing, and the weath­er dry and sun­ny. But even mechan­i­cal weed con­trol can­not do every­thing. Tine har­rows, for exam­ple, have vir­tu­al­ly no effect on crust­ed soils. There is also an increased risk of frost dam­age after mechan­i­cal weed con­trol. Fur­ther­more, it is dif­fi­cult to use with­in the row and espe­cial­ly on estab­lished weeds.

Mechan­i­cal weed con­trol and pre­ci­sion farming 

Since a great deal of pre­ci­sion is required dur­ing mechan­i­cal weed con­trol, tech­ni­cal pre­ci­sion farm­ing meth­ods exist to sup­port this type of work. For exam­ple, auto­mat­ic steer­ing sys­tems keep the equip­ment on track by using GPS data. When using these sys­tems, it makes sense to use the same machine routes for both sow­ing and mechan­i­cal plant pro­tec­tion. A suit­able field plan­ning appli­ca­tion enables you to opti­mal­ly coor­di­nate con­sec­u­tive work steps. Tar­get­ed action between the rows depends on the GPS sig­nal. That is why farm­ers use real-time kine­mat­ic (RTK) tech­nol­o­gy for greater accu­ra­cy. Lumps and bumps on the field sur­face cre­ate addi­tion­al hur­dles which can knock imple­ment tools out of align­ment. Enhanced pre­ci­sion can also be achieved by using sen­sors. Sen­sors analyse the crops and guide the blades close­ly along­side the main crop. This accu­rate­ly removes unwant­ed growth. In addi­tion to sen­sors that detect rows, there are some that also iden­ti­fy dif­fer­ent plant species. Plant iden­ti­fi­ca­tion apps have been avail­able on the mar­ket for quite a while now. As farm­ing process­es become more robo­tised, the strengths of these apps can be used more fre­quent­ly for mechan­i­cal weed con­trol. How­ev­er, it will be a while before ful­ly autonomous machines such as robots become wide­ly used in farm­ing. ‘Con­cept vehi­cles’, on the oth­er hand, are already being test­ed on select­ed tri­al fields.

Yas­min Moehring

Tel. +49 30 25 93 29–901
Mobil +49 151 17 28 18 69
moehring@365farmnet.com