Hi!
soybean don't need urea, because the atmosfere nitrogen have cost off, but, if we use urea, how much more production we can increase? and if have other crop after soybean, how this urea can help? If we use urea slower up?
Thank you !
Gustavo
I think urea increases production in many plants, especially in corn, wheat, barley, rye, as well as in forage crops that are cultivated in the cold season of the year. In leguminous plants, the root microorganisms that fix and assimilate free nitrogen, urea has no effect on their production.
Sokrat
Soybeans are high in protein and therefore in nitrogen. In fact, soybeans remove about 4 lbs of N from the soil for each bushel of grain produced. This compares to less than a lb of N removed per bushel of corn grain produced. The soybean plant's N needs are usually supplied by nitrogen-fixing rhizobia bacteria associated with its roots, so adding nitrogen fertilizer is usually unnecessary under normal production practices
However, applications of N during the pod or seed stages of soybean development can increase yield. N applications during vegetative soybean growth stages have been shown to reduce early nodulation, and were not beneficial to yield.
Following are for increasing of Soybean yield
1. Urea to be added in pod or seed stages
2. Tillage
3. weed control
4. Soybean Inoculants(the addition of "extenders" prolongs the life of bacterial cells when inoculants are applied to seed long before planting or when seed is treated with a fungicide)
5. Harvest Practices (Soybeans dry down very rapidly after physiological maturity, and pods readily lose and re-absorb moisture. After several cycles of wetting and drying, pods are predisposed to shatter. To prevent shattering losses, harvest soybeans the first time they reach 13 to 14% moisture.)
Hello Gustavo,
actually, we study the urea cycling in soybean leaves. During nitrogen remobilization urea is produced by arginine degradation and then urea is converted in ammonium and CO2 by urease. So, urease is very important for Nitrogen remobilization in soybean plants.
Answering your question soybean can complete its life cycle very well without any input of extra nitrogen when it is nodulating.
For other crops, it will depend, seems in many cases, combinations among urea and another nitrogen source can be promissory.
For soybean https://www.frontiersin.org/articles/10.3389/fpls.2015.00888/full
As the legumes are fixing the Nitrogen from the environment, they don't need the nitrogen fertilization. However, low rate (10-15lb/acre) of Nitrogen is applied to the legumes which are grown in more sandy or low organic matter containing soil as a starter to provide nitrogen before the N2 fixation starts. And, the crop following the legumes, especially in cereals, yield increases.
In Brasil the soils are acid oxisols for the most part.
The sole reliance on urea would potentially increase issues with soil acidity and the Nitrogen only fertilization would cause increases of nutrient balance.
Generally for a Brasil situation liming to prevent toxicity and use of materials which are capable of providing complete nutrition would be recommended.
If you go conventional ag route take a complete soil test make sure you address the acidity issues and use complete fertilizer which gives complete nutrition.
In organic use compost which can give an ability to have organic produce. Soil test needed regardless.
I think the surrounding environmental conditions in which soybean is grown can play a major role in determining whether or not the plant needs to be fertilized by adding urea or not, This is also related to the effect of the environment on the activity of bacteria that fixed atmospheric nitrogen .
Soybean with robust biological nitrogen fixation does not require urea. In addition the addition of urea will turn off the more cost effective biological nitrification plus urea will contribute to increase soil acidity. If there is a nitrogen concern the best way to address is to seed inoculate with effective Rhizobium strains.
The presence and activity of Rhizobia bacteria for soybean depends on effective inoculation. This can be done by seed treatment or by granular application to the soil. The granular application can deliver more bacteria takes more material and might be more effective. The seed application is more economical but the final decision would best be determined by a test to determine the efficacy and results versus the cost. In area that has not grown soybean the effective strains are not inhabiting the soil. The areas which have a history of soybean production may not have any compelling reason for inoculation but people may practice it as an insurance. In a cropping system featuring soybean the soybean strains are likely to be in sufficient numbers to make inoculation unnecessary.
Soybean does best in a slightly acid environment. At pH less than 5.7 and less than 5.1 the environment is favorable for manganese and aluminum toxicities, respectively, however. In the alkaline soil pH soybeans can show iron, manganese and zinc deficiency. The optimal rhizobium activity is dependent of moderate pH and sufficiency in essential micronutrients. The rhizobia bacteria need Mo Co Zn and B for optimization. Along with Rhizobium inoculation the use of micronutrient seed treatment can be useful together will Phosphorus in an acid soil rock phosphate is very useful. Since the air is 80% nitrogen the soybean has no real need in urea when the biological nitrogen system is managed. The addition of nitrogen as urea will reduce the biological nitrification system and acidify the environment unnecessarily. Under the protein deficient environment in the tropics the identification of local ability to strategically lime and the ability to get optimized symbiosis is important. In low soil P environments the soybean has been shown to respond to mycorrhizal inoculation with is synergistic with Rhizobia inoculation in field and laboratory trials. When soybean is grown optimally not only is there no need for urea or other nitrogen fertilizer but when biological nitrogen fixation is optimized the residual soil nitrogen can provide a rotation effect in a crop like maize of 18% higher yield potential and the fertilizer N need for the maize can be reduced about half.
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