Promising management strategies to improve crop sustainability and to amend soil salinity

by Ajay Kumar Mishra, Rout George Kerry, Bisworanjita Biswal, Trisha Sinha, Sheetal Sharma, and Mukesh Kumar

The FAO estimated that over 6% of the world’s land area and about 20% of irrigated croplands are affected by salinity. Strategic and adaptive research on the incorporation of modern technologies, salt-tolerant varieties, biochar, plant growth regulators, and nanoparticles will be critical in amending salt-affected soil and increasing the productivity of degraded land.

Plants are encountering several environmental adversities caused both by living and non-living factors, with the former known as biotic stress and the latter as abiotic stress. Various stress factors have been found in almost all environments and climatic conditions, but salinity stress seen in plants growing under arid and semi-arid conditions should be given priority. Salinity stress is a form of abiotic stress, which is caused due to salt accumulation in the root zones of plants, making them physiologically flaccid and unfit for production.

Currently, approximately 1.1 × 10⁹ ha of land is salt-affected globally, and saline soils are increasing at an alarming rate of 1.5 million hectares annually. The FAO estimated that over 6% of the world’s land area and about 20% of irrigated croplands are affected by salinity.

Nearly 95% of the total degraded land in India (7.5 million hectares) is accounted for by soil salinity/alkalinity, especially found in the states in the northwestern part (Western Uttar Pradesh, Punjab, Haryana, northern Rajasthan, and Delhi), the central part (Gujarat, central and western Rajasthan, Maharashtra, and Madhya Pradesh), and the northeastern part (West Bengal, central and eastern Uttar Pradesh, Bihar, and eastern Odisha) of India.

Containing profuse neutral soluble salts (chlorides and sulfates of sodium, magnesium, and calcium), saline soils inhibit the growth of plants growing in them. These soils are characterized mainly by a highly elevated water table, the escalated salinity level of underground water, and poor drainage conditions, leading to ceased aeration of the affected soil. Soil salinity affects soil microbial activity and diversity, which in turn disturbs various vital activities in soil, viz., residue decomposition, soil respiration, and nitrogen (N) transformations.

The combinations of these problems have rendered large tracts of land unproductive, with direct economic losses. Salinity is developed naturally through primary or human-induced secondary salinity. In a plant system, salt can have an effect in three ways, viz., reducing water potential, which results in osmotic stress, induced ion imbalance or disturbing ion homeostasis, and ion toxicity due to the excess accumulation of ions in plant cells.

The majority of physiological processes in plants, including seedling germination, growth, photosynthesis in leaves, and nutrient and water uptake by vascular bundles, are affected by salt stress leading to a decrease in yield, although the type and degree of these effects vary with crops, their growth stages, and their sensitivity to a saline environment.

The unwise and random use of fertilizers also results in soil salinity, leading to a decrease in crop productivity. Therefore, it is necessary to adopt technologies that could improve crop production, crop residue utilization, and soil fertility.

Due to its more significant potential in enhancing soil physicochemical properties, the organic matter could be a game changer in modifying the saline environment into a stable and healthy crop environment. Improving soil structure, aeration, and aggregation increases the probability of a higher crop yield and healthier soil.

Understanding the impacts of salinity both on soil health and plant physiology is necessary to mitigate their adverse effects on crop production. However, there are a few age-old soil salinity remediations, such as leaching or flushing excess salt with quality irrigation water up to the required root zone and regularly scraping the surface salts.

In contrast, considering that water scarcity will be a huge problem that will affect crop production worldwide, mostly in arid and semi-arid regions, in the next few decades, sustainable ways to remediate the adverse effects of soil salinity on crop growth and ultimately crop production need to be emphasized.

Therefore, this review article is focused on discussing the responses of plants under salinity stress and improving plant performance under a saline environment through various sustainable approaches.

Soil degradation, particularly through salinity, impedes the productivity of croplands and thereby poses challenges in securing livelihoods. A multidimensional approach has shown promising results in reducing soil salinity in different Indian agroecological situations.

Strategic and adaptive research on the incorporation of modern technologies, salt-tolerant varieties, biochar, plant growth regulators, and nanoparticles will be critical in amending salt-affected soil and increasing the productivity of degraded land.

Because of diversification into other sectors, cultivable land in India is shrinking; the restoration, amelioration, and management of salt-affected soils appear promising for land expansion and production enhancement to ensure food and livelihoods.

Soil quality characteristics are commonly used to assess sustainable land management in agroecosystems. Over the last two decades, several land management studies have been conducted in India and elsewhere regarding reducing the salinity and improving the productivity of the land.

Unfortunately, there is insufficient data to provide critical remarks on the best working and eco-friendly techniques that should be practiced for salinity remediation in the enhancement of crop production.

Plant-associated microorganisms as biofertilizers can promote agriculture yield and soil status under saline soil. These organisms constitute endophytic microbes and symbiotic fungi in the rhizoplane and rhizosphere and they act in many ways, such as initiating the osmotic reaction, growth hormones, and nutritional elements, working as biocontrol agents by inducing specific genes in crops.

Biochar and crop residues could be used to ameliorate salinity stress by improving the physical and thereby biological status of the soil and reducing the uptake of Na+ by plants. At present, nanotechnology is being adapted for specific nutrient availability purposes, and it is also being used for conserving soil fertility and reducing the impacts of salinity on the soil.

Many studies have revealed that tree plantations and agroforestry systems could efficiently be applied as remediation and restoration strategies for degraded and marginal lands. Many salt-tolerant species or halophytes with potential agricultural or industrial value can be grown in degraded saline areas as cash crops or commercial crops.

Proper land evaluation is considered an essential component for managing any degraded lands, including salt-affected ones, to model the best suitable cropping practices to achieve a sustainable agricultural system. In the field of salinity, research is needed, particularly on land evaluation and opportunities for salinity management in the agroecosystem to enhance land productivity.

Globally, soil salinity poses a severe menace to food security and threatens millions of small and marginal farmers’ livelihoods. Low-cost, need-based, site-specific restoration and amelioration programs should be strategically planned and implemented in order to counter soil salinity.

Developmental research on integrating modern technologies, salt-tolerant varieties, biochar, PGPR, and nano-gypsum will be of great significance in reducing salt-affected soil and increasing the productivity of degraded lands.

In addition to technological solutions, socio-economic and political considerations are critical in mitigating soil salinization. Farmers need to be provided with various incentives rather than subsidies to undertake corrective salinity measures.

Read the study:
Mishra AK, Das R, George Kerry R, Biswal B. Sinha T, Sharma S, Arora P,  and Kumar M. (2023). Promising management strategies to improve crop sustainability and to amend soil salinity. Frontiers in Environmental Science, 10

Related stories:

New research project to develop salt- and flood-tolerant rice for Africa within five years
Rice feeds 3.5 billion people globally, and provides up to 20% of the world’s daily calorie consumption. However, climate change is threatening the global annual rice harvest of approximately 800 million tons. A new research project, with funding from the Danish Government, seeks to remedy this by developing new rice cultivars tolerant of future climate change scenarios.

The development of new, robust rice cultivars within the proposed time span of five years is made possible through the use of biotechnological tools but does not include genetic modification. Researchers and students from the University of Copenhagen and Sokoine University of Agriculture in Tanzania will collaborate closely with experts from the International Rice Research Institute (IRRI), who have previously succeeded in developing climate-smart rice for Asian farmers.

Green Super Rice (GSR) traits: Breeding and genetics for multiple biotic and abiotic stress tolerance in rice
The Green Super Rice (GSR) breeding strategy began in 2008 at IRRI to efficiently develop lines with multiple-stress tolerance and more nutrient- and water-use efficiency with high genetic gains for various targeted ecosystems. The development of superior rice varieties with the GSR breeding approach under decreased rates of fertilizer, pesticide, and irrigation water, grown in marginal environments and producing fewer greenhouse gas emissions, and with improved grain nutrient elements. GSR breeding aims to develop stable high-yielding GSR rice varieties with several green traits suitable to be grown under lower input conditions in irrigated and rainfed areas of Asian and African countries.

Bangladesh combats the “white plague”
Each year, during the boro season (November-May), salinity is so high that a white film of salt covers paddy fields in the coastal areas of Bangladesh. For Bangladeshi farmers, this white color on top of their soil is a warning sign that their land is “sick.” Salinity is even dubbed the “white plague” in Australia’s newspapers and magazines, which indicates the seriousness of the problem when it strikes. Salinity affects around 1 million hectares in Bangladesh. Some climate experts say that sea-level rise will cause the country’s landscape to become “sicker.”