Pre­ci­sion Farm­ing for the cere­al har­vest – har­vest­ing via satel­lite images

Preci­sion Farm­ing uses sen­sors and satel­lites to man­age spe­cif­ic field areas. Such issues as soil irreg­u­lar­i­ties or dif­fer­ences in the pro­duc­tiv­i­ty of a field are tak­en into con­sid­er­a­tion and can be man­aged using dig­i­tal field map­ping. This enables tar­get­ed sow­ing, fer­til­i­sa­tion, plant pro­tec­tion treat­ment as well as har­vest­ing and can reduce the use of resources. Over­all, Pre­ci­sion Farm­ing can be used in almost all oper­at­ing areas:

• Farm man­age­ment (farm man­age­ment and qual­i­ty management)
• Stock man­age­ment (sow­ing, fer­til­i­sa­tion, plant pro­tec­tion, harvest)
• Machin­ery man­age­ment (site mon­i­tor­ing, machine mon­i­tor­ing and con­trol, route planning)
• Work man­age­ment (auto­mat­ic steer­ing, manned and unmanned guid­ance and satel­lite vehicles)

When it comes to the cere­al har­vest, Pre­ci­sion Farm­ing can facil­i­tate qual­i­ty dif­fer­en­ti­a­tion on the field itself. This reduces the need for more dif­fi­cult sep­a­ra­tion process­es using post-har­vest tech­nol­o­gy. For exam­ple, a par­tial area can be dif­fer­en­ti­at­ed by mois­ture con­tent using test dri­ves or yield maps from past years. Anoth­er option is dif­fer­en­ti­a­tion based on the con­stituents of the crops in dif­fer­ent areas. This can be done by sep­a­rat­ing the col­lect­ing tanks or leav­ing low­er-qual­i­ty areas of the crop.

Satel­lite images as the basis for har­vest­ing decisions

Qual­i­ty dif­fer­en­ti­a­tion on the field can be checked by review­ing the veg­e­ta­tion by means of satel­lites. The Euro­pean Coper­ni­cus pro­gramme includes var­i­ous mea­sur­ing sta­tions (on the ground, in the water and in the air) and satel­lites. These con­tin­u­ous­ly record data on the state of the Earth, which are processed for cli­mate stud­ies, weath­er fore­casts, wind ener­gy maps and har­vest sta­tis­tics. The satel­lites and instru­ments were devel­oped by the Euro­pean Space Agency, ESA. The first satel­lite, Sen­tinel-1A was launched in 2014. Cur­rent­ly, the Sen­tinel satel­lite fam­i­ly con­sists of six dif­fer­ent mis­sions: Sen­tinel 1, 2, 3, 5P and 6, plus Sen­tinel 4 and 5, which oper­at­ed as mea­sur­ing instru­ments on mete­o­ro­log­i­cal satellites.

Sen­tinel 2 satel­lites are opti­cal satel­lites that were launched in 2015 (Sen­tinel-2A) and 2017 (Sen­tinel-2B). All of the 13 chan­nels are opti­mised for the obser­va­tion of land sur­faces and veg­e­ta­tion. The images range between 443 and 2190 nm in the vis­i­ble and infrared spec­trum. The high res­o­lu­tion (of 10, 20, and 60 m) and a sam­pling width of 290 km ensures that veg­e­ta­tion can be very well iden­ti­fied. It is thus pos­si­ble to observe the growth of wild and crop plants, esti­mate har­vest fore­casts and map forests. Bio­mass growth can thus be checked and assessed through the spa­tial res­o­lu­tion of the nutri­tion­al sta­tus of the crop plants. How­ev­er, the raw data of the satel­lites are of lit­tle use. They must first be processed, for exam­ple in the form of appli­ca­tion maps. In some cas­es, the satel­lite data are off­set against addi­tion­al data such as tem­per­a­ture data or old­er satel­lite data. For exam­ple, the appli­ca­tion maps can be sup­ple­ment­ed by addi­tion­al infor­ma­tion, such as the fer­til­iz­er used or the har­vest maturity.

Opti­mise your cere­al har­vest by deter­min­ing ripeness and threshability

Nowa­days, the com­bine only enters the field for the cere­al har­vest once the grain is dry. This was dif­fer­ent when cere­al crops were har­vest­ed by hand. The grain was put into tem­po­rary stor­age before being processed in the thresh­ing machine. Dur­ing this time the straw was able to con­tin­ue ripen­ing, the mois­ture con­tent in the grain was min­imised and the husks loos­ened so that the grains could be extract­ed more eas­i­ly from the ears. With mech­a­ni­sa­tion and the use of com­bine har­vesters, thre­sha­bil­i­ty in the field has become increas­ing­ly rel­e­vant. The mois­ture con­tent of the straw and the grain, the grain sep­a­ra­tion and the ratio of straw mass to bio­mass are espe­cial­ly cru­cial here. Thre­sha­bil­i­ty tends to be a sub­or­di­nate objec­tive in cere­al breed­ing. In prac­tice, when select­ing vari­eties it is cru­cial to ensure that the vari­eties are sta­ble in terms of lodg­ing, shat­ter loss­es and grain dam­age, that they are easy to hull, husk and de-awn in the com­bine har­vester, and that the grain and straw ripen as simul­ta­ne­ous­ly as pos­si­ble. Fur­ther­more, the vari­eties should have good stand­ing pow­er, release well, cut well and be resis­tant to break­age. The mois­ture and strength of the straw are huge­ly impor­tant for com­bine capac­i­ty and com­bin­ing damage.

All fields are often ready to har­vest at the same time. This can be a prob­lem. Ide­al­ly, the har­vest­ing times should be planned when the fields are sown. This makes it pos­si­ble to extend the har­vest peri­ods by stag­ger­ing ripeness lev­els. The har­vest time win­dow can be expand­ed with the choice of vari­eties and loca­tions (het­ero­ge­neous dis­tri­b­u­tion of ear­li­er and lat­er vari­eties in dry and moist loca­tions) and, depend­ing on the weath­er, dif­fer­ent sow­ing times. This plan­ning is very com­plex and requires high-lev­el agri­cul­tur­al exper­tise. How­ev­er, unfavourable weath­er con­di­tions in the har­vest sea­son can some­times thwart these plans. Final­ly, the thre­sha­bil­i­ty of the field must be ascer­tained in order to select an opti­mal com­bine set­ting and work organ­i­sa­tion. The thre­sha­bil­i­ty man­u­al­ly is test­ed by means of a straw twist test, where­by a bun­dle of straw is removed from the field. The tough­ness and mois­ture can be esti­mat­ed by twist­ing the straw with both hands. In addi­tion, some ears are removed from dif­fer­ent crop heights and the grains rubbed out. This pro­vides an indi­ca­tion of the firm­ness of the husks. In addi­tion, the stress sen­si­tiv­i­ty of the grains is assessed. In com­bi­na­tion, con­clu­sions can thus be drawn on the ripeness of the grain.