Despite that soybean [Glycine max (L.) Merrill] is easily introduced in places where it is not native, its production, especially Africa is constrained by the lack of Bradyrhizobium japonicum which is needed for biological nitrogen fixation (BNF). Inoculating soybean with proper rhizobacteria is a key solution to enhance benefits of BNF. A study was done in Northern Tanzania in Arusha and Kilimanjaro regions to assess the effects of B. japonicum, nitrogen (N) and phosphorus (P) application on four selected soybean varieties namely Uyole 1, Uyole 2, Uyole 3 and Uyole 4. Inoculation with B. japonicum strongly (P
THE EFFECT OF MIXED PLANTING OF BIRDSFOOT TREFOIL, SAINFOIN, SUBTERRANEAN CLOVER AND TALL FESCUE ON NODULATION AND NITRATE REDUCTASE ACTIVITY IN SHOOTS | Journal of Global Agriculture and Ecology
The Institute of Forage Crops in Pleven, Bulgaria (2011-2012) conducted a pot trial to investigate nodule biomass, nitrate reductase activity, and biochemical composition of birdsfoot trefoil, sainfoin, subclover, and tall fescue, both alone and in combination. Birdsfoot trefoil (100 percent); sainfoin (100 percent); subterranean clover (100 percent); tall fescue (100 percent); birdsfoot trefoil + tall fescue (50:50); sainfoin + tall fescue (50:50); birdsfoot trefoil + subterranean clover + tall fescue (50:50); birdsfoot trefoil + subterrane (33:33:33). When compared to nodulation in pure crops, birdsfoot trefoil and subclover in binary mixtures with tall fescue generated 15.1 and 15.4 percent more nodules. Tall fescue, on the other hand, inhibited sainfoin nodulation by 25.0 percent. The number of nodules considerably increased when the third component (i.e. subclover) was added to the mix (by 18.5 percent ). Except for long fescue, all legumes studied showed an increase in nitrate reductase activity in the leaves
The total amount of plastid pigments was found to be lower in blends of birdsfoot trefoil and tall fescue, but higher in mixtures of sainfoin and subclover and tall fescue. The aboveground bulk of birdsfoot trefoil has the greatest crude protein content (15.07 percent ). When compared to pure legumes, water soluble carbohydrates in combinations were much higher, while tall fescue had significantly lower.
Please see the link :- https://www.ikprress.org/index.php/JOGAE/article/view/580
STRATEGIES FOR IMPROVING NODULATION AND NITROGEN FIXATION OF LEGUMINOUS CROPS TO ENHANCE PRODUCTION IN SMALLHOLDER FARMING SYSTEMS | Journal of Global Agriculture and Ecology
Leguminous crops play a unique function in biological nitrogen fixation, which allows them to fix atmospheric nitrogen in the soil. In the presence of nitrogenase, biological nitrogen fixation is a natural way of converting atmospheric nitrogen (N2) to ammonia in a form that plants can use. Farmers in Sub-Saharan Africa face an issue with low agricultural productivity. Low yields in leguminous crops are a result of diminishing soil fertility, reduced N2-fixation, soil acidity, overcultivation, and poor soil management methods, all of which cause soils to be nitrogen and phosphorus deficient, rendering them prone to erosion and resulting in land degradation. It has been found that organic matter treatment elevated soil pH from 5.0 to 6.5 after 90 days. The majority of farmers in Sub-Saharan Africa cannot afford the high prices of mineral fertiliser, so much of it is imported, putting a strain on foreign exchange. As a result, farmers are recommended to intercrop with legumes or undertake crop rotation to assist enhance soil nitrogen levels and thus production. This review paper aims to disclose techniques to improve legume nodulation and nitrogen fixation in smallholder farming systems in order to boost production.
Please see the link :- https://www.ikprress.org/index.php/JOGAE/article/view/821
Habineza M. Jean Pierre, Josiah M. Kinama, Florence M. Olubayo, Susan W. Wanderi, James W. Muthomi, Felister M. Nzuve University of Goma (UNIGOM), Goma, Democratic Republic of Congo (DRC) Department of Plant Science and Crop Protection, University of Nairobi, Nairobi, Kenya Kenya Agricultural and Livestock Research Organisation (KARLO), Kenya Key words: Maize, Intercropping, Soybean, Nodulation, Soil fertility.
This study was carried out to determine the effect of intercropping Maize with Soybean on soil fertility. The study was conducted at two sites and evaluated three Soybean varieties (hybrid SB19, GAZELLE – a local variety, hybrid TGX1990-5F) as sole crop and intercropped with maize, with maize pure stand as control. In the intercropped plots, one row of Soybean was planted after every alternate row of maize. Data collected included soil nutrient status before planting and at harvest and nodulation in soybean. Variety TGX1990-5F had significantly more nodules followed by GAZELLE and SB19 was the last in sole crop and in intercrop at Embu during long rains and short rains (p ≤ 0.05). Mwea produced more nodules compared to Embu. Intercropping maize and soybean had no effect on the number of nodules per plant both seasons.
Effective nodulation of mungbeans can fix about 60 to 70 kgN/ha, sufficient to grow a 1 t/ha crop. If the rhizobial inoculant is not applied or if the bacteria are exposed to high temperatures and die, this nitrogen will need to come from residual N reserves in the soil or from a pre-plant application of urea or Big N.
The survival of Rhizobia bacteria is very low if the inoculant product is exposed directly to the hot sun and temperatures above 33–35 degrees C. It only takes a few hours of exposure to the sun and high temperatures on the back of a paddock truck or in seed bins ready for planting for high levels of mortality to occur, rendering the inoculation process ineffective.
Even if you have grown mungbeans in the paddock in the past, you simply rely on a large enough population of the mungbean strain (Group I) of Rhizobia being present in the soil. Water injection into the seeding furrow using cool water of neutral pH is the best application method to promote rhizobial survival and efficacy.
Avoid mixing inoculant with liquid fertilisers. Even though liquid fertilisers are a very desirable nutrient application option, rhizobia are very sensitive to pH and direct contact with elements such as copper and zinc.
Some farmers are now adopting the practice of applying nitrogen prior to planting mungbeans to make their planting operation very smooth and staff efficient. Keep in mind that these nitrogen applications should be pre-plant and not just at planting because a wetting front is required to push this relatively mobile nitrogen deeper into the soil profile, where the roots of the young mungbean plants are developing. There is no sense applying nitrogen into dry-ish topsoil while the mungbean roots develop in a good moisture zone lower in the profile. This is particularly important in fast growing mungbean crops where there is very little time to fix a nutrient deficiency.
If you plan to use applied nitrogen rather than (or as well as) fixed nitrogen to meet the mungbean crop’s needs, a nutrient analysis of the soil profile well in advance of planting will help avoid having a sad, nitrogen-deprived mungbean crop three to four weeks after planting. There is no advantage in applying a high rate of nitrogen fertiliser and also applying inoculant, because rhizobia will only fix nitrogen effectively if the soil nitrogen levels are low. However, if your applied nitrogen remains positioned in the drier top soil layer, then seed inoculation may still be very effective.
More about rhizobia survival
Rhizobium bacteria are able to live freely in the soil without a host for a time but generally only when soil conditions, especially pH, are favourable to their survival. Rhizobia and their host legume tend to have similar pH tolerance. Inoculation is generally recommended for pulses (other than lupins) grown on soils with pH below 6 (CaCl2) or below 6.5 (in water).
In higher pH soils, rhizobia associated with all pulse crops can survive for several months without a host plant. Many growers choose to use inoculant every time they grow mungbeans to be sure that the crop will nodulate effectively and fix atmospheric nitrogen to at least meet its own needs.
High biomass crops and narrow row spacing promote increased nitrogen production through fixation, contributing more to the N-budget of the rotation.
Fifty-eight million years ago, the ancestor of soybean (Glycine max) and barrel clover (Medicago truncatula) went through a whole genome duplication. It did so in reaction to the environmental stress caused by the same event that wiped out dinosaurs. As a result, some duplicated genes disappeared (fractionation), some genes and their new copies split functions that used to be carried by the original gene (subfunctionalization), or the new copy of a gene would take on an entirely new function (neofunctionalization). Nodulation, or the ability that legumes have to live in symbiosis with bacteria that fix nitrogen on their behalf, is a feature that resulted from this whole genome duplication.
This is also thought to have accelerated the split between cool- and warm-season legumes, from what would become soybean (Gm) and barrel clover (Mt), something that occurred 54 million years ago. Lastly, 13 million years ago, soybean went through a second whole genome duplication. What you see about is a comparison of a 150-kb region between the two legumes' genome. As you can see, more duplicated genes have been lost in the barrel clover than in soybean, partly because of this second duplication event 13 million years ago.
Learn more in the article Genome-Enabled Insights into Legume Biology, written by Nevin Young, of the University of Minnesota in St Paul, and Arvind Bharti, of the National Center for Genome Resources, for the 2012 Annual Review of Plant Biology.
Also, listen to an audio conversation with Nevin Young about the topic, and subscribe to our iTunes podcast feed.
