Maize nurse crop – Secure maize yields and pro­mote biodiversity

Despite adher­ing to good pro­fes­sion­al prac­tice, maize cul­ti­va­tion in some loca­tions can be fraught with prob­lems. Ero­sion dur­ing the juve­nile devel­op­ment of the slow-clos­ing maize, nitro­gen out­puts or soil com­paction after the har­vest are just a few of the pos­si­ble dif­fi­cul­ties that farm­ers are faced with. Nurse crops can help in these areas and can even bring oth­er eco­nom­ic advan­tages. For exam­ple, the cul­ti­va­tion of nurse crops is eli­gi­ble for fund­ing in some fed­er­al states in Germany.

As the reg­u­la­to­ry require­ments asso­ci­at­ed with crop cul­ti­va­tion are con­stant­ly increas­ing, nurse crops are becom­ing increas­ing­ly more inter­est­ing, par­tic­u­lar­ly in maize cul­ti­va­tion. Due to its com­par­a­tive­ly slow devel­op­ment, wide row spac­ing and growth height, the crop is par­tic­u­lar­ly good for plant­i­ng with nurse crops. It’s also eco­nom­i­cal­ly inter­est­ing to use a catch crop or field for­age as a nurse crop as it helps farm­ers to save both work­ing time and costs.

How­ev­er, for both con­ven­tion­al and organ­ic farms the advan­tages and dis­ad­van­tages of using nurse crops must be weighed up care­ful­ly due to the unavoid­able com­pe­ti­tion between the main crop and nurse crop for water and nutri­ents! If the nurse crop is unsuc­cess­ful, it then com­petes with the main crop with­out hav­ing any pos­i­tive effects.

Advan­tages of nurse crops in maize cultivation

In most cas­es, plant­i­ng nurse crops along­side maize brings many agri­cul­tur­al, eco­nom­i­cal and eco­log­i­cal advan­tages. Here are some exam­ples of these advantages:

• Nurse crops loosen up tight maize crop rota­tions, increase and secure yields.
• They can have pos­i­tive effects on bio­di­ver­si­ty and soil life by encour­ag­ing bio­log­i­cal activ­i­ty in the soil and humus for­ma­tion. This is par­tic­u­lar­ly impor­tant as maize itself does not make any par­tic­u­lar con­tri­bu­tion to humus formation.
• Nurse crops store nutri­ents, pre­vent leach­ing and pre­serve the nutri­ents for the sub­se­quent crop. They can help to ful­fil many water pro­tec­tion requirements.
• The dense growth sup­press­es seed-prop­a­gat­ed weeds and helps farm­ers to save mon­ey in plant pro­tec­tion as it is almost a form of inte­grat­ed plant pro­tec­tion. It should be not­ed, how­ev­er, that there is only a lim­it­ed range of her­bi­cides that can be used depend­ing on the select­ed nurse crop. As such, a split appli­ca­tion is recommended.
• Nurse crops increase the load-bear­ing capac­i­ty of the soil and pro­tect it against com­paction dur­ing the har­vest­ing. The strong root pen­e­tra­tion improves the tilth, which in turn ben­e­fits the sub­se­quent crop.
• The grow­ing crops pro­vide pro­tec­tion and nutri­ents for wild ani­mals and can be used as green manure, a bio­gas sub­strate or fod­der the fol­low­ing spring.
• In organ­ic agri­cul­ture, nurse crops can be used to sup­ply nitro­gen and pre­vent weeds thanks to their nitro­gen-fix­ing prop­er­ties and the fact that they sup­press seed-prop­a­gat­ed weeds. How­ev­er, they usu­al­ly can­not replace mechan­i­cal weed control.
• Maize nurse crops can be count­ed as eco­log­i­cal focus areas and as such can help farm­ers to ful­fil green­ing require­ments. To do this, these areas must be main­tained until the 15^th of Feb­ru­ary of the fol­low­ing year.

What do you need to pay atten­tion to with nurse crops plant­ed with maize?

The species com­po­si­tion and sow­ing date of the nurse crops is deter­mined by the soil mois­ture and weath­er con­di­tions. They should not be sown too ear­ly in regions with sum­mer droughts in order to stop the nurse crops from com­pet­ing with the maize for avail­able water dur­ing its sen­si­tive juve­nile stage. Depend­ing on the sow­ing process, the quan­ti­ties to be spread varies between 10 and 15 kg (for row seed­ing) and 20 kg (for broad­cast or slur­ry seeding).

Sev­er­al dif­fer­ent sow­ing meth­ods are suit­able and can be used at dif­fer­ent times of the year and with vary­ing mix­tures of grass­es and legumes. Ear­ly nurse crops can be sown direct­ly with the maize if there is enough water for the two crops. Lat­er mix­tures can be sown into the exist­ing plant pop­u­la­tion with a fer­tilis­er spread­er or togeth­er with the slur­ry. A suit­able plant pro­tec­tion strat­e­gy is deci­sive for the suc­cess of a nurse crop!

After har­vest­ing the cov­er crop, the growth of the nurse crop is stim­u­lat­ed by the strong light stim­u­lus, and pos­si­bly also encour­aged by the break­ing up of the maize stub­ble. The hardy crops can remain until the spring and then be used in var­i­ous dif­fer­ent ways: as green manure for humus for­ma­tion and nitro­gen sup­ply, as a bio­gas sub­strate or in cat­tle feed. If they are in good con­di­tion, they can even be used for cut­ting. The prop­a­ga­tion of grass seeds also offers an oppor­tu­ni­ty to eco­nom­i­cal­ly exploit the nurse crop.