Role of Legumes in Improving Soil Fertility Status

*Muthuraman Yuvaraj, Muthaiyan Pandiyan and Pandurangan Gayathri*

#### **Abstract**

Legume plants have a probably important role to play in growing indigenous nitrogen production besides meeting human demands for protein and energy. Some legumes have the capability to solubilize in any other case unavailable phosphate by excreting organic acids from their roots, in addition to improving soil fertility. Legumes also assist to restoration of soil natural matter and limit pest and disease issues when used in rotation with nonleguminous crops. Research has shown that the organic nitrogen fixation procedure is the most environment friendly way to grant the giant amounts of nitrogen wished through legumes to produce highyielding crops with an excessive protein content. For the fixation technique to occur, legume vegetation must enter into a "symbiotic" or collectively beneficial partnership with sure microorganism known as rhizobia. Soon after legume seeds germinate, rhizobia current in the soil or delivered as seed inoculum invade the root hairs and go through an infection thread toward the root. The bacteria multiply rapidly in the root, causing the swelling of root cells to structure nodules.

**Keywords:** legume, soil fertility, greenhouse gas, crop rotation

#### **1. Introduction**

Global populace will hit 9.6 billion human beings with the aid of 2050 [1] and will face world challenges among which attaining meals security, reducing the risk of local weather exchange through lowering the net release of greenhouse gases into the ecosystem and assembly the increasing demand for energy are the most critical ones. In particular, the impact of climate trade and related biotic and abiotic stresses to which crop structures will be an increasing number of uncovered pose serious implications for global food production [2].

To meet these challenges, a policy framework needs to be developed in which the sustainability of production consumption patterns turns into central. In this context, meal legumes and legume-inclusive manufacturing systems can play essential roles by means of turning in more than one offerings in line with sustainability principles. Indeed, legumes play central roles [3]: (a) at food-system level, both for human and animal consumption, as a source of plant proteins and with an increasingly importance in enhancing human beings health [4]; (b) at production-system level, due to the capability to fix atmospheric nitrogen making them potentially notably appropriate for inclusion in low-input cropping systems, and due to their function in mitigating greenhouse gases emissions [5]; and (c) at cropping-system levels, as diversification vegetation in agroecosystems primarily

based on few important species, breaking the cycles of pests and diseases and contributing to stability the deficit in plant protein manufacturing in many areas of the world.

Legumes have a probably substantial position to play in enhancing soil carbon sequestration. They can also have considerable additional advantages beyond their significance involving nitrogen fixation and excessive protein feeds. These consist of advantageous impacts on biodiversity and soil quality. There is a great need for a strong focus on creating the role of legumes and their contribution to each the sustainable intensification of manufacturing and the livelihoods of small holder farmers in many components of the world [6]. Apart from their makes use of as food and fodder they have a very necessary position in retaining soil fertility by fixing atmospheric nitrogen and enhancing soil structures and adding organic matters. Moreover, it is generally used as an intercrop and covers plants, and sometimes, it is cultivated as emergency vegetation due to its brief life cycle. Since it requires low fertilizer and other inputs this crop is relatively profitable in a most economical point of view. It also improves environmental quality by sequestrating carbon and mitigating other pollutants. Legumes are additionally a potential plant team in which some of the species having a capacity of remediating poisonous metals and organic pollutants [7].

## **2. Nitrogen fixation**

Legume plant and seed tissue is distinctly high in protein. This can be without delay attributed to a legume's capability to supply most of its personal nitrogen wants with the assist of symbiotic Rhizobia microorganism residing in their roots. Inoculated with the applicable stress of Rhizobia bacteria, legumes can furnish up to 90% of their own nitrogen (N). Shortly after a legume seed germinates in the presence of Rhizobia microorganism in the soil, the bacteria penetrate the root hairs and cross into the root itself. The bacteria multiply, inflicting a swelling of the root to shape pale pink nodules. Nitrogen gasoline present in the soil air is then sure by the microorganism which feed on carbohydrates manufactured by the above-ground plant in the course of photosynthesis [8]. The bacteria produce ammonia (NH3) from the hydrogen obtained from the plant's carbohydrates and nitrogen from the air. The ammonia then provides a supply of nitrogen for the plant to grow. This symbiotic relationship between bacteria and legume lets in them both to flourish and produce a high-protein seed or forage crop. Even although legumes can repair nitrogen from the atmosphere, they can take up large quantities of soil nitrogen if it is available. Nitrogen release from a legume crop occurs as the above-ground plant residues, roots and nodules step by step decompose. Soil microorganisms decompose the highly nitrogen-rich organic cloth and launch the nitrogen to the soil when they die. Usually about two-thirds of the nitrogen fixed through a legume crop becomes handy the subsequent growing season after a legume in a rotation [9].

#### **3. Advantages of legumes in soil quality**

Soil quality advantages of legumes include increasing soil natural matter, improving soil porosity, recycling nutrients, improving soil structure, decreasing soil pH, diversifying the microscopic lifestyles in the soil, and breaking disease build-up and weed problems of grass-type crops.

**19**

**Figure 1.**

*Role of Legumes in Improving Soil Fertility Status DOI: http://dx.doi.org/10.5772/intechopen.93247*

As stated previously, legumes are high in protein, and therefore, nitrogen rich.

Several legumes have aggressive taproots reaching 6–8 feet deep and a half inch in diameter that open pathways deep into the soil. Nitrogen-rich legume residues inspire earthworms and the burrows they create. The root channels and earthworm burrows make bigger soil porosity, promotion air movement and water percolation

Because perennial and biennial legumes root deeply in the soil, they have the capability to recycle crop nutrients that are deep in the soil profile. This effects in a more environment friendly use of utilized fertilizer and prevents nutrients (particularly nitrate nitrogen) from being lost due to leaching under the root region of

The improvements are attributed to increases in more stable soil aggregates. The protein, glomalin, symbiotically along the roots of legumes and other plants, serves

Because most crop residues incorporate a lot extra carbon than nitrogen, and microorganism in the soil need both, the nitrogen provided by legumes allows the decomposition of crop residues in the soil and their conversion to soil constructing

**3.1 Soil natural rely**

natural matter.

**3.2 Soil porosity**

deep into the soil.

**3.3 Recycle vitamins**

**3.4 Improve soil structure**

shallower-rooted crops in the rotation (**Figure 1**).

*Benefits of legume crop in improving soil sustainability [10].*
