Is soybean a millet

Weed control in soybeans

Large-grain legumes such as field beans and field peas are an important part of crop rotation in organic farming. In addition to the necessary protein feed base from our own, safe cultivation, the nitrogen replenishment by the nodule bacteria is an indispensable basis for demanding subsequent crops such as bread grain or potatoes. In relation to conventional cultivation, however, these indigenous protein fodder crops are so far no more than niche crops for internal use. According to the current political will, this should change radically. The Free State is investing 2 million euros in an "action program for domestic protein feed", in particular to significantly reduce the high level of dependence on soy imports for animal husbandry. These are very ambitious goals for growing grain legumes.
Soy cultivation in Bavaria
In Bavaria, in contrast to neighboring Austria, soy cultivation was previously a niche in the niche of legume cultivation. The cultivation was supported by regional marketing programs such as “Our Land” because soy cannot be completely replaced as protein feed in pig and poultry farming. In order to even come close to achieving the core objective of the new action program, which is largely independent of soy imports, soy cultivation in Bavaria would at least have to be expanded significantly. In addition to the necessary establishment of soy as a regular market crop in the trade and processing industry, many farmers are required above all to integrate the new crop into their crop rotations. With a share of around 8% of the Bavarian arable land that covers demand, soy could then develop its high crop rotation value and make large amounts of nitrogen fertilizer superfluous. With the "soy cultivation boom" initiated since 2010 (soy cultivation area in Bavaria 2019: 15,700 ha), this development has already been set in motion, which in future will have to be borne by the market by rewarding local production.

Weed control in soybean cultivation

Newcomers to soy cultivation must, in particular, quickly become familiar with the special rules of the game for weed control. Successful weed control secures an average of 20 to 30% yield and is therefore an elementary production measure. A failure in weed control can also lead to a total loss of the harvest. Legumes have only hesitant youth development. Weeds and grass weeds can develop undisturbed on the correspondingly long open soil surface and the culture can literally "overgrow".
The main competitors for the soybean are key weeds such as burdock bedstraw, chamomile, knotweed, goosefoot, melde or rape seed. Root weeds such as thistles and dock are particularly feared because they can hardly be controlled mechanically or chemically. Soy is often integrated into corn crop rotations. Regularly occurring types of millet can easily be combated in the soy with special graminicides (herbicides with a purely grass effect).
Due to the relatively low level of competition in the youth phase, particularly weed-growing locations are not very suitable for soy cultivation. Any existing old weeds must also be removed before sowing by cultivating the soil or using glyphosate in a targeted manner.

Chemical weed control in soybeans

A number of registered herbicides for weed and weed control are available for conventional cultivation (see table). In general, the pre-emergence method is the main area of ​​application for broadly effective weed control. In post-emergence, only weeds and a few weeds can be controlled safely. In order to support the potential for action and the crop compatibility of the soil herbicides in the pre-emergence process, a fine-crumbly seedbed preparation and precise sowing technology are indispensable.

Pre-emergence treatments as a standard measure

The basis for sustainable weed control is pre-emergence treatment with suitable broad-spectrum herbicides. In order to achieve a sufficient effect against the common leading weeds and often also types of millet, tank mixes of various herbicides are necessary in the pre-emergence treatment. Useful combinations here are Artist + Centium, Spectrum + Sencor, Spectrum + Sencor + Centium and Stomp Aqua + Spectrum. The tank mix from Artist + Centium is a relatively robust solution for all locations with medium to heavy soils and corresponding weeds. However, the high level of effectiveness is also bought at relatively high costs. With the triple combination of Spectrum + Sencor WG + Centium, it is possible to adapt the application rates to the specific weed pressure of the location and thus keep costs under control.
When using Stomp or the active ingredient Pendimethalin, there is a certain risk: The cultivation tolerance of Pendimethalin in soy is based on what is known as position selectivity, i.e. the active ingredient applied to the soil surface is only absorbed to a very limited extent by the deeper-rooted soy plant, so that under normal conditions no major damage to the culture is caused.
In extreme spring precipitation, however, the active ingredient can get into the radicle zone and cause damage and thinning. Stomp Aqua should therefore only be used in regions with little rainfall (Northern Bavaria) with an application rate of no more than 2.0 l / ha.
In the case of preparations with the active ingredient Metribuzin (Sencor Liquid, Artist), there are variety-specific intolerances which, however, were only clearly noticeable in our experiments with the variety "ES Mentor".

Few options for dicot post-emergence treatment

The Post-emergence preparations Clearfield-Clentiga and Harmony SX® are available for post-emergence treatment against dicotyledon weeds that may be necessary, for example if the soil herbicides have an insufficient effect due to drought. Harmony SX is particularly effective against chamomile, rape, shepherd's purse and hellerkraut, dock, amaranth and hollow teeth. A splitting application at intervals of 10 to 14 days in the 2 to 4 leaf stage of the weeds as well as supplementing with the additive Trend increase the reliability of effectiveness. Clearfield-Clentiga has a broader effect against e.g. amaranth, Frenchweed, burdock, goose foot, melde, hollow tooth, hellerkraut, dead nettle, chickweed and black nightshade. In addition, the preparation has a side effect against grass weeds. Due to the relatively high price, however, CL-Clentiga is less suitable for situation-related post-treatment, but should rather be used as a strategic spray sequence treatment, e.g. with Spectrum Plus pre-emergence.

Weed grasses - no problem in soybeans

Mercury and seed grasses can be controlled in the soy in a targeted and highly effective manner with the graminicides Focus Ultra® or Fusilade Max®. The pure grass remedies should be used in the 2 to 3 leaf stage of the seed grasses or when the couch grass grows 15 to 20 cm at the latest. Subsequent treatments always run the risk of excessive shading by the cultivated plants, with the result that the weed grasses absorb too little active substance and corresponding losses of effectiveness. The addition of suitable additives or wetting agents promote the effectiveness of the graminicides very effectively. The Focus Ultra preparation is therefore marketed in a pack with the Dash® additive. In this combination, 50% of the regular application rates of Focus Ultra are sufficient for weed control.

additional Information

Mechanical weed control in soybeans

The purely mechanical weed control places high demands on the treatment management and is also heavily dependent on the site conditions. Due to the weed competition in the youth development, several applications with harrow or hoe are unavoidable. If the sowing dates are somewhat later, mechanical weed control can practically begin before sowing, in that the seedbed preparation is brought forward and the first wave of weed germs is eliminated before sowing with light harrowing or a sharp harrow. Due to the deep seed placement, a blind harrow is recommended before emergence. This must be done with great sensitivity in order not to damage the seedlings. When emerged, soybeans are too sensitive for harrow treatment, which can only be carried out again from the third pair of leaflets. The unavoidable damage to the pot on the crop can be compensated for by increasing the seed strength. With larger row widths, hoeing devices can also be used successfully. This eases the deadline pressure for mechanical weed control and larger or more strongly rooted weeds can still be controlled well. Similar to maize, the soil can be thrown onto the row to a certain extent in order to prevent the further development of the weeds in the row by spilling them. In addition to combating weeds, mechanical care promotes gas exchange and thus the development of nodule bacteria.
The use of hoeing devices is problematic in locations at risk of erosion. The loosened uppermost soil zone absorbs water relatively well in the beginning of heavy rain, but in the case of intensive rainfall it can also lead to an early and increased washing away of the soil. Slopes with a gradient of over 10% are therefore generally unsuitable for the use of intensive mechanical weed control. On less steep surfaces, a certain risk reduction can be made by cultivating across the slope. In the case of adjacent surface waters, additional protective measures with buffer zones between the waters should be implemented.