Soil and water conservation practices in dryland ecosystems: A comprehensive review

productivity in these areas (Spitalniak et al., 2019; Wani & Kumar, 2002). The advantages of SWC technologies are well documented but the promoted practices have not been widely adopted mainly due to limited awareness of the benefits and appropriate application (Hamado, 2011; Mutiso et al., 2018) [55, 19, 34] . Other studies indicate that information should be tailored to the individual needs of individual farmers to increase adoption rates. This review critically assesses SWC practices relevant to dryland farming, focusing on their mechanisms, impacts on productivity, and contributions to climate resilience. The objectives are to: (i) synthesis current knowledge on SWC practices; (ii) evaluate their effects on crop productivity and resource use efficiency; and (iii) identify research gaps and future directions for the sustainable intensification of dryland farming systems.

Concept and Classification of Dryland Farming

Drought farming is the cultivation of agricultural crops under conditions of low annual rainfall insufficient to support the crop. Based on rainfall and length of growing season arid agriculture is classified as arid, semi-arid and semi-arid (Table 1). Arid areas receive less than 250 mm of rain annually and have limited possibilities for cultivation. With the rain-fed approach, a wider range of crops can be grown in semi-arid areas (250 to 750 mm of rain). Mixed cropping and animal husbandry and reliance on traditional knowledge are typical of dryland farming systems which generally have low use of external input. Reddy (2000). Note: Semi-arid in the text (250-750 mm) refers to the agro-ecological sub-zone; Table 1 figures follow Reddy's system.

Characteristics of Dry Farming

According to Reddy (2000) climate has a significant effect on crop production in India in an arid climate which accounts for about 62 percent of the total 142 million hectares and 42 percent of the total food production. Irregular and uneven rainfall and high rates of evaporation in such climates often cause water shortages, which have a serious impact on the stability of crop production. Singh (1995) [44,53] points out that the variation in the growing season from 60 to 300 days is due to variations in total rainfall, distribution, potential evapotranspiration and water retention in soil. In these areas, the soil is characterised by poor quality and nutrient deficiencies, especially calcium, phosphorus, sulphur and nitrogen. Important soil orders are vertisols, alfisols and related.

Characteristics and Challenges of Dryland Farming

Systems: Dryland farming systems are characterized by annual rainfall amounts that are less than the potential evaportranspiration. Moisture deficits limit the growing season, and long term droughts during the growing season result in low agricultural production in arid regions. Dry soils are shallow, sandy and have low level of soil organic carbon and nutrients. According to FAO and ITPS (2015) and LAL (2020) drylands are particularly prone to soil erosion by wind and water [13,30] . Soil erosion, surface crusting, reduced infiltration, depletion of nutrients and gradual decline of soil organic matter leading to loss of soil fertility and water-use efficiency, fragmented landholdings, limited financial resources, poor access to improved technologies and weak institutional support are the major challenges to improve the resilience and productivity of dryland farming systems. Therefore, the soil and water conservation measures need to be adapted to the local agro-ecological and socio-economic conditions (Rockstrom et al., 2010; FAO & ITPS, 2015) [46,13] .

Soil Degradation and Water Loss Processes in Drylands

Land degradation due to soil erosion in arid ecosystems is one of the most serious environmental problems in the world. In particular, soil degradation due to soil erosion substantially decreases the earth's ability to sustain life. The loss of productive topsoil by soil erosion will have serious consequences not only for man but for all living organisms as the topsoil is that layer of the earth (soil) where vegetation grows and the soil supplies vital nutrients and organic matter to support vegetative growth. Common types of erosion are water (especially in areas with high amounts of rainfall) and wind (in arid or semi-arid areas typically having very low to no vegetation, dry soils, and frequent high winds). Both types of erosion gradually degrade soil structure, reduce the soil's ability to hold water, reduce the amount of water the soil can hold and lower the productivity of agricultural lands. Loss of soil organic matter from erosion will further reduce the stability of the aggregates making up the soils thus increasing susceptibility for further erosion. Soil and water conservation (SWC) practices involve protective soil cover to reduce soil degradation through improved water absorption into the soil (increased infiltration), reduced runoff and enhanced stability of aggregate structure in soils, thereby maintaining soil fertility and increasing agricultural productivity over time (Lal, 2001; FAO & ITPS, 2015; Morgan, 2005) [31,32] .

Soil Erosion

Soil erosion is a problem for the land and farms that grow food, especially in dry areas. This problem happens when the soil gets broken up and moved somewhere else by things like water and wind. When it rains a lot there is excess water for the soil to absorb. The water runs over the surface of the land.

Removes the good soil and nutrients plants need to grow. The degree of water erosion is influenced by factors such as the type of rainfall, steepness of land, type of soil, degree of plant cover on land and care given to land by people. But in dry areas where there is not much plant cover it remains dry for long periods and the soil is loose and sandy, wind erosion is a greater problem. This makes it easy for the wind to pick up particles of soil and move them around. This problem has been discussed by Morgan and Lal (Morgan, 2005 and Lal, 2001) [31,32] . Erosion causes not only soil erosion but also the removal of all nutrients important for plant growth from top soil including Soil Organic Matter (S.O.M), Nitrogen (N), Phosphorus (P) and other nutrients. The soil is also degraded besides causing these losses due to Erosion. Therefore, when water falls on the surface of eroded areas due to erosion, it makes it very difficult or impossible for the soil to infiltrate the ground and gather enough water to be usable by plants. The cumulative effects are such that farmers are left with sites where it is very difficult to grow viable crops or crops that will help maintain agricultural productivity and drought preparedness. Erosion leads to the washing of soil erosion into rivers and reservoirs, diminishing their capacity to hold water. This also has implications for downstream ecosystems (FAO & ITPS, 2015) [13] . Sustainable soil and water conservation (SWC) practices such as cropping on contours, conservation tillage, mulching, use of vegetative barriers and agroforestry are important for the long-term health of soils, improved water use efficiency and continuing sustainable food production systems (Lal, 2001; Morgan, 2005) [31,32] in our dryland farming systems to reduce runoff velocity, maintain a healthy soil surface, improve infiltration and maintain soil fertility.

Runoff and Infiltration Losses

The availability of soil water for crops grown in a dryland agricultural system is influenced by both runoff and infiltration processes. Limited infiltration capacity of dryland soils means that many dryland crops cannot benefit from rainfall. Raindrops will generate surface runoff because they cannot break up and disperse the existing soil aggregates that form crusts (surface sealing) and prevent and impede water infiltration. Repeated tilling, machinery traffic, and animal grazing cause soil compaction, which reduces the pore space in the soil and the water availability in the rooting zone of plants. The net effect is that most of the rainwater will run off the surface of the soil rather than into the soil, thus increasing the potential for soil erosion by movement of water, and decreasing the amount of water available for plants to use when extracting soil moisture (Morgan, 2005; Lal, 2020) [31,32] . Low soil infiltration can reduce the amount of moisture stored in the soil, decrease the efficiency of water use by crops, and make crops more susceptible to moisture stress during dry periods, ultimately reducing crop growth and yield. But there are areas in arid and semi-arid where rainfall is infrequent and I think there is little opportunity for them to occur. Soil and water conservation practices can help improve the soil structure and increase water infiltration, decrease runoff velocity and increase holding capacity (by adding organic matter). These techniques will promote improved water use efficiency to help ensure that farms will remain productive in the long term in dryland areas (FAO & ITPS 2015; Rockstrum et al., 2010) [13,46] .

Evaporation and Transpiration Losses

Evapotranspiration and transpiration are two of the primary components of evapotranspiration and both are major drivers of water use rates found in dryland agriculture. In arid/semiarid areas the high temperatures, very bright solar radiation, low (and changing) relative humidity and often very windy conditions, has led to a large percentage of the rainfall to evaporate before it can be used by plants for uptake. Nonproductive evaporation to the extent that it reduces moisture storage in soil, reduces available moisture at the root zone of crops (Rockström et al., 2010; Allen et al., 1998) [46,1] . On the contrary, transpiration is thought to be a productive use of water, as it helps in physiological processes such as nutrient transport, photosynthesis and biomass growth, which are all part of the overall growth of crops and therefore increased yield. SWC practices aim at reducing evaporation and at the same time maximizing productive transpiration. These practices mulching, conservation tillage, retaining crop residues, planting cover crops, and planting trees act as protective covers over the soil to reduce soil temperature, slow wind at the soil surface, and prevent direct evaporation of water. In addition, these types of practices improve both the structure and water entry and storage capabilities of the soil, providing more water to support crop growth. SWC practices help conserve soil moisture and produce increased crop transpiration from rainwater than evaporation from rainwater, thereby increasing water-use efficiency, improving crop sensitivity to drought, and supporting sustainable agricultural practices in dryland environments (FAO & ITPS 2015, Lal 2020) [13,30] .

In-Situ Soil and Water Conservation Practices

In-situ soil and water conservation techniques (SWC) are effective tools for the conservation of soil moisture, organic matter, enhancement of nutrient availability and development of healthy soil ecosystem. Their effectiveness is maximized if they are adapted to the topography, soil type, precipitation patterns, and cropping systems. These techniques are low cost and environment friendly options to enhance agricultural productivity and are applicable for sustainable dryland farming especially in arid and semi-arid regions of the world as they reduce erosion, and increase crop resilience to drought. (Diop et al., 2022; Birhanu et al., 2024) [3,11] .

Conservation Tillage

Conservation tillage is an agricultural practice that involves reduced tillage of the soil and leaving some of the crop residues on the soil surface. Conservation tillage differs from conventional tillage (which involves multiple runs with a plow and harrow) in that at least 30% of the residue remains on the ground after planting with the four main types of conservation tillage (minimum tillage, reduced tillage, and zero tillage). The residue on the surface prevents the movement of the sediment. It slows down the falling rainwater when it hits the ground. This retains moisture and benefits farmers as it does not lose the moisture through evapotranspiration or run-off when the rain falls. Conservation tillage decreases soil disturbance through reduced tillage operations, resulting in increased numbers of soil aggregates, greater soil pore space and increased water infiltration into the soil, so that more water is held in the root zone of plants (Hobbs et al., 2008, Kassam et al., 2019) [20,25] . Through conserving tillage, the oxidization of soil organic matter is reduced and crop residue is gradually buried in the soil, resulting in the accumulation of soil organic carbon. More soil organic matter will increase aggregate stability, increase rates of nutrient cycling, promote increased microbial activity, and increase the ability of the soil to store and retain moisture, thus providing long term benefits to soil fertility as well as increasing drought resiliency. In addition, less fuel, less labor and greater profits result from conservation tillage systems than conventional tillage systems. Conservation tillage practices are very important.

These methods are compatible with conservation agriculture.

Examples of ideas include managing crop residuals and diversified cropping rotation. Conservation tillage and these other practices are elements of conservation agriculture. They help in the efficient use of resources and maintain high agricultural productivity. This is especially true for dryland farming systems. (Selvakumar and Sivakumar, 2021; FAO, 2022) [48,14] . The Conservation Tillage method is also known as Zero tillage/No Tillage It is used to sow directly into the soil with minimum disturbance and keeping the crop residue on the surface of the soil. The Indo-Gangetic Plain has seen a great increase in the use of ZT in the rice-wheat cropping system resulting in increased irrigation water requirement, timely sowing of wheat by farmers and reduced production costs. Tillage elimination results in lower fuel and labour outputs; it is responsible for lower greenhouse gas emissions; and it contributes to climate change mitigation through enhanced soil carbon storage (Jat et al., 2014; Kassam et al., 2019) [23,25] . A major constraint in adoption of CA is the shortage of crop residue for surface application particularly in peninsular and western India where crop residues are mainly used as fodder (Singh & Venkates warlu, 2009). Furthermore, many tropical semi-arid (SAT) soils may require intensive primary tillage to increase the infiltration of rain water, where deep tillage by a plough or chiselling helps in improving crop growth and yields (Channappa, 1994) [5,51] . [12,20] Minimum Tillage (Reduced Tillage)

Tillage practices have been reduced in scale and intensity from what we see in conventional tillage.

15-30

Conserves soil moisture, reduces erosion, also decreases labor and energy requirements. (Lal, 2015; FAO, 2001) [29,14] .

Mulch Tillage

Crop residues are left on the soil surface which is >30 Enhances water retention, controls weeds, and improves soil fertility.

( Phillips Phillips, 1984; FAO, 2001) [14, 41] .

achieved through minimal tillage.

Strip Tillage

In some rows which have the seeds the tilling is done; between the rows we leave the soil undisturbed.

>30

Improves soil bed structure at the same time that it maintains residue cover and reduces erosion.

(Reicosky & Allmaras, 2003) [45] .

Ridge Tillage

Crops are grown on raised beds from the prior season's planting.

>30

Improves soil aeration, root growth, and erosion control (CTIC, 2023) [8] .

Chisel Tillage

Soil is broken up by chisel plows which do not turn over the full profile.

30-50

Reduces soil compaction, improves water infiltration, and also maintains residue cover. (Lal, 2015). Chisel Tillage [29] 5.2 Terracing This is done by transforming the steep slope into a series of flat or slightly angled steps, separated by embankments that help to shorten the length and reduce the angle of the slope.

Changing the slope in this way retards the velocity of the water that run-off the surface. This gives water from precipitation more time to be absorbed into the ground and reduces the chances of the soil being washed away. Terraces will help retain precipitation at its point of fall increasing the level of moisture available in the soil, enhance recharge of groundwater aquifers and create a more conducive environment for growing crops particularly in hilly and mountainous areas (Morgan, 2005; Walia et al., 2024) [32,57] . Terraces are constructed in different shapes depending upon slope, soils, rainfall, type of land use or cropping system. For example, bench terraces are made in the same way you would make steps on a steep hill. This helps you reduce soil erosion and can be used as a method for growing crops. Broad-based and narrow-based terraces are mainly used in gentle and moderate slopes and the graded terraces usually provide a small slope, so they have the capacity to safely transfer runoff, during heavy rain, to a stable outlet. The selection of these designs will be largely dictated by the soils, the crop systems or agriculture, the steepness of the land, rainfall amounts etc. (Sharma et al., 2023; Morgan, 2005) [49,32] .

Contour Farming

In addition to aiding in the conservation of nutrient-rich topsoil through reduced sediment transport and elimination of soil organic matter loss, contour farming is improved in its ability to reduce runoff and improve crop productivity when used in conjunction with other conservation measures such as contour bunds, vegetative strips, and conservation furrows. Integration of contour and conservation furrows has been demonstrated to improve rainfall infiltration, increase soil moisture storage and increase crop yields under rain fed conditions. Economic evaluations of these integrated practices show a 12%-23% increase in benefit-cost ratio in comparison to the conventional flat farming methods by improving water conservation practices, reducing degradation of soil, and increasing crop productivity (Walia et al., 2024; Morgan, 2005). This contour farming is a suggested low cost, easy and sustainable technique for enhancing productivity of land and conserving soil and water resources in dry land areas [32,57] .

Land Configuration Techniques

The Broad Bed and Furrow (BBF) is a widely used agronomic practice in semi-arid Vertisols. The system consists of broad beds (approximately 95 cm) with shallow furrows (approximately 55 cm wide and 15 cm deep) between the beds. The beds are usually on slopes of 0.4% to 0.8% so that the furrows can drain excess rainwater, while still providing enough moisture for the root zone. This BBF will play a role for the reduction of waterlogging and moisture deficit during the growing season at the same time. Other systems of land management like ridges and furrows or tied ridges also aid infiltration and runoff, by storing water for later use in the furrows. These systems have been shown to increase crop yields, save soil moisture and improve the efficiency of the overall resource use of rainfed systems (ICRISAT, 2009; Pathak et al., 2009) [22,40] .

Tied Ridges

Tied Ridging is a very good in-situ soil and water improvement practice to increase the efficiency of rainwater harvesting and to conserve soil moisture in dryland agriculture. Tied ridging (or Tied Ridging) is a variation of the traditional ridge and furrow planting method, where short earth-mounds known as cross-bunds (or ties or furrow dikes) are built periodically across the concave between the ridges and furrows of the conical planting method. The cross-bunds divide this area into several sub-basins that hold on to any water that runs off, temporarily, and give it an opportunity to soak into the ground, instead of flowing down a hill. This process considerably reduces the speed/velocity of water, reduces soil erosion and increases the amount of available soil water for the crops growing in the root zone thereby helping in improved crop performance in rainfed situations. (Critchley et al., 1991; Wani et al., 2003) [9,60] .

Mulching

Soil conservation methods, such as mulch, will help protect, promote, help reduce soil erosion and improve the moisture retention of soils through installing a layer of either organic material (e.g. straw, crop residues, wood chips) or nonorganic material (e.g. plastic sheeting) on top of the soil surface. Mulch on the soil surface reduces raindrop impact and formation of soil crust and will maintain the soil structure and improve soil aeration, root penetration and water infiltration. Mulching slows down the runoff from a rainstorm while absorbing the energy from falling rain and preventing nutrient off of the surface of the soil which promotes long-term soil fertility (Osman, 2018; Lal, 2020) [37,31] .

Strip Cropping

Strip cropping is a practice of growing erosion-resistant crops in strips parallel to the slope of the land to conserve water and soil in situ. The strips slow surface water runoff, allow more rainwater to soak into the ground and trap sediment carried in running waters. There are three benefits from limiting soil erosion and maintaining the moisture in the soil that increase the productivity of the land over a period of time. The strips also form a natural barrier to catch any runoff, anchor the soil to the surface and reduce the loss of topsoil and nutrients. Strip cropping is an effective measure to increase productivity of gently sloping rainfed and dryland agricultural lands while enhancing the long-term health of the soil (Morgan, 2005; FAO & ITPS, 2015) [14,32] . Various grasses and shrubs can be used to construct vegetative barriers for soil preservation depending upon the local agro-climatic conditions. Grasses like vetiver (Vetiveria zizanioides), sewan (Lasiurus sindicus), sania (Crotalaria burhia), and kair (Capparis decidua; depending on the literature used Capparis aphylla may be used to refer to kair) can be used for soil conservation because these grasses are effective in filtering out sediments, reducing the velocity of runoff, and preventing soil erosion. Another grass commonly established on field bunds is Gliricidia sepium. It has an extensive root system which stabilizes embankments, thus reducing soil erosion. Gliricidia provides green biomass rich in nitrogen for green manuring. It acts as a source of biological nitrogen fixation which in turn improves the fertility of the soil. Gliricidia provides valuable fodder and fuelwood. Therefore, it can be inferred that the combination of strip cropping and vegetative barriers significantly improves soil conservation, increases water use efficiency, and ultimately contributes to the long-term sustainable production of agriculture in dryland ecosystems (Morgan, 2005; Lal, 2001; FAO & ITPS, 2015) [14,32] .

Cover Crops and Green Manuring

In-situ soil and water conservation practices like green manures and cover crops improve soil quality, prevent soil erosion and increase the sustainability of agriculture. Cover crops and green manures are planted during the fallow period of time and/or between cash crops to maintain a cover (hydraulic) on soil surface. The runoff from the area is less, and the protection that cover crops and green manures give to the soil from the impact of falling raindrops is reduced. Cover crops and green manures have large root systems which bind the particles of the soil and reduce soil compaction, improve soil aggregation and improve pore connectivity. All these factors lead to improved water infiltration, aeration and greater amount of soil moisture available to plants. Moreover, the presence of a living vegetation cover reduces the loss of water by evaporation from the soil and controls the growth of weeds, both of which contribute to an improved efficiency of water use in dryland farming systems (Blanco-Canqui et al., 2015; Lal, 2020) [4,30] .

Agroforestry Practices

Agroforestry is a sustainable land use system in which trees and crops are grown together and often animals as well, to improve the use of resources and create eco-stable ecosystems and to produce more food. Agroforestry will protect the soil by integrating trees into agricultural enterprises. It conserves soil and water and offers economic and environmental benefits. Trees and shade create a wind tunnel that slows winds and protects soil from erosion by wind. The tree canopy provides a cooler temperature to the soil, less evaporation and a microclimatic condition that is beneficial to crop growth. The litter from the leaves, the turnover from the roots and the residue from the pruned materials will all add organic matter to the soil and will contribute to improve the soil nutrients, soil aggregation, microbes and the soil's ability to hold water. Deep rooted trees will also take nutrients from deeper soil profiles and improve the soil structure with their large root systems creating a more porous soil which will allow for more infiltration and reduce surface runoff (Jose et al., 2021; Nair, 2011) [24,36] .

Ex-Situ Soil and Water Conservation Measures

Ex-situ Soil and Water Conservation (SWC) is the collection, storage and use of the excess runoff water from catchments for the needs of agriculture, domestic and livestock particularly in drought situations. This practice helps farmers to access water during periods of low rainfall, reduces the loss of water through evaporation, encourages the recharging of ground water and stabilize crop production in both rain-fed and water-scarce regions. Also, ex-situ SWC practices also lead to increase in agricultural productivity and resilience of farming systems to drought and climate variability as stated by Rockstrom et al., (2010) and Rao et al., (2022) [46,43] . Soil ex-situ Farm ponds, tanks, reservoirs and underground cisterns are commonly used to capture and store runoff from high intensity rainfall events for later use during periods without enough water. Additional Irrigation applied at specific points in the crop growth cycle helps to minimize the negative impacts of irregular rainfall and extended drought periods on rainfed agricultural systems throughout the year. Rainwater harvesting is very important in arid and semi-arid areas, because the amount of precipitation is low and unreliable. so it is necessary to manage the rain water.

Rainwater harvesting is a system that collects rainwater (via pipes) that falls on the roof surface and directs the collected water into a designated storage container (like a tank, reservoir, pond or cistern). Rainwater has solutions for its collection in many forms such as; on-farm ponds, contour trenches, percolation pits, recharge wells and check dams. These systems capture surface runoff and increase groundwater recharge, add moisture to the soil and lessen erosion. These systems increase crop yields, improve the availability of reliable irrigation water and provide a more beneficial use of the limited water available, improve resilience to droughts and promote the sustainability of dryland agriculture (Desai, 2021; FAO, 2014; Rockstrom et al., 2010) [10,15,46] .

Rainwater Harvesting

Rainwater harvesting (RWH) is one of the most favored practices for conservation of soil and water resources which are available outside the soil where the rain falls as harvested water. Rainwater harvesting is commonly used in agriculture, livestock management or households. RWH systems can be used as a supplement to irrigation in areas with variable or unreliable precipitation such as arid and semi-arid areas and can help to mitigate the effects of drought during critical periods of the crop growing cycle by providing additional irrigation at those times. Ponds, tanks or reservoirs, and wells are structures for the establishment of RWH systems. All these structures are used to collect rainfall runoff from land because of high intensity storm events. RWH systems help in reducing evaporative losses of water by delaying the period between receiving rainfall and using the water for irrigation and enhance the reliability of irrigation by providing a sufficient supply of water throughout the growing season (Rockstrom et al., 2010; Desai, 2021) [46,10] .

Check Dams

Small hydraulic structures made of stone, masonry, concrete, gabion wire mesh, logs, sandbags or compacted earth, constructed across drainage channels, such as gulleys or seasonal streams, to slow the flow of water through that channel to assist in controlling soil erosion, to trap sediment carried by the water, and to assist in recharging groundwater by allowing more time for water to soak into the soil. Check dams help to slow down the runoff from rainfall so that it has less power/force (because it slows down) to erode soil and to encourage the deposition of sediment. To give more time for the water to infiltrate into the soil and to give more moisture in the soil and to create a larger quantity of groundwater. Hence, check dams are an important component of watershed management and the conservation of water resources and play an especially important role in arid and semi-arid regions where the amount of rainfall is highly variable (Critchley et al., 1991; FAO, 2017) [9,15] .

Percolation Pits and Trenches

Percolation pits and trenches are popular forms of ex-situ soil and water conservation systems that are intended to capture the flow of water produced by surface runoff and allow for increased levels of groundwater recharge. These structures will catch rainfall and/or surface runoff before it has a chance to leave the landscape, which allows for gradual infiltration of water into the soil profile. By slowing down the flow of surface runoff and encouraging infiltration, these structures can help to reduce erosion, reduce the amount of sediment carried by surface runoff, and to enhance the overall hydrologic balance of agricultural watersheds. In general, percolation pits are used in areas that are producing moderate volumes of surface runoff, while trenches are generally used for sloping areas where fast flowing surface runoff limits natural (background) rates of infiltration (Qin, 2020; FAO, 2017) [42,16] . Percolation pits are short holes dug into the ground and filled in with large rocks or gravel to allow rainwater to seep into the earth's surface more rapidly to help recharge underground sources of water, typically 1 to 2 m deep. Percolation trenches are channels dug parallel to the hills to prevent erosion of soil by intercepting the runoff and helping retain water after it rains; they are on average between 0.3 m and 0.6 m deep depending on how steep the slope is and the length of the channels often varies. Contour channels are similar to percolation trenches; they are used to reduce runoff, increase water availability during drought, increase soil moisture, and reduce gully development by slowing the rate that water travels across an area. Both of these structures enhance groundwater recharge, add to water supplies in periods of low rainfall, raise the production capacity of rainfed crops and increase the sustainability of agriculture. These two types of structures are important in reducing the impact of drought, conserving soil and providing a sustainable supply of freshwater resources when combined with other watershed management techniques, in arid or semi-arid climates (Critchley et al., 1991; Qin 2020) [9,42] .

Micro-Irrigation Techniques

Micro-irrigation is very efficient, providing water directly to the crop root zone in accurately metered amounts. This prevents loss of water (evaporation, runoff and deep percolation) as it supplies water to crops as required and provides for both drip (delivering a drop of water at a time to the roots of a plant) and sprinkler type modes of application (distributing water uniformly to the soil surface). Use of micro-irrigation also improves water-use efficiency due to increasing optimum soil moisture, better nutrient absorption through fertigation (application of fertilizer through irrigation system), lesser weed growth, better crop yield and quality. Micro irrigation is suitable for arid and semi-arid areas with less water resources & need for water management. Microirrigation also saves water, reduces soil erosion, reduces energy use and improves both the efficiency and sustainability of farming through improved irrigation efficiency & conservation of resources (Patel et al., 2023; FAO, 2017; Howell, 2001) [38,16,21] .

Watershed-Based Approaches

The watershed based approach is an ex-situ soil and water conservation approach to manage rainfall, runoff and sediment at a landscape level as opposed to field level. A watershed based approach is based on structures to harvest / store / control excess runoff (check dams, percolation tanks, farm ponds, gully plugs and diversion channels) to decrease peak runoff volumes, control soil erosion and improve the availability of water for agricultural use through ground water recharge. The integration of watershed management with integrated land-use planning processes (vegetative restoration and efficient use of natural resources) through participatory watershed development programs involving communities in planning and implementation of these programs contributes to increased irrigation potential, reduced land degradation, improved crop productivity and strengthened resilience of rainfed farming systems. Thus, watershed-based conservation (Wani et al., 2008; Rockstrom et al., 2010) [59,46] can result in sustainable agriculture and durable water security in arid and semi-arid environments.

Comparative Effectiveness of SWC Practices

A key challenge in the SWC literature is the lack of a common comparative framework for assessing the effectiveness of practices across soil types, rainfall zones and farm sizes. Table 4 presents a context-specific reference using evidence synthesized from referenced studies.

Determinant of the Adoption of Soil Bunds for soil and water conservation:

The probit model was statistically significant at the significance of level of 1%, as indicated by the p-value of the likelihood ratio chi-square (Table 5). The age of the decision maker influenced the adoption of soil bunds negatively, and it was statistically significant at 5% level of significance. This implies that younger farmers are more willing to adopt soil bunds. This result is in line with that of other studies. Higher probability of adoption of younger farmers can be attributed to the fact that, generally, benefits of soil and water conservation cannot be realized within a short time period; therefore, older farmers do not have much incentive for investing in conservation efforts. In the study area, we noticed that younger farmers were more educated, had more access to the required information and technologies and also had a better understanding of negative consequences of soil erosion and land degradation, resulting in a higher probability of adoption. Furthermore, we also observed that younger farmers wanted to pursue marketoriented farming and were also aware about the importance of sustaining natural resources. Contrary to our expectation, education had a negative albeit statistically insignificant influence, and similar findings were also reported by many researchers For this, it was argued that better education might offer opportunities for alternative livelihood options, making for less interest in farming and thereby reducing the chances of investment in soil and water conservation. As per prior expectations, family size and farm size had a positive influence on the adoption, but it was statistically insignificant. As anticipated, CREDIT had a positive effect on adoption of SWC practices. In the study areas, most of the farmers were resource-poor, having a limited capacity for investing in conservation efforts. Therefore, having a source of off-farm income helps with overcoming the liquidity constraints. The result is in agreement with previous studies showing a positive effect of access to credit on the decision to take up soil and water conservation measures (Kumar et al., 2020) [26] . [7] .

Strategies for Improving Adoption of SWC Practices

The implementation of improved soil and water conservation (SWC) practices has been demonstrated to bring significant benefits to soil health, water-use efficiency, and agricultural productivity; but the adoption rate of these practices is low among many dryland producers. Farmers' decisions to adopt conservation technologies are influenced by technical and economic factors, but also by institutional support, government policies, market access, social customs, community participation and household resources. Therefore, the implementation of SWC practices needs to be promoted through integrated approaches that deal with the biophysical and socio-economic challenges (Knowler & Bradshaw, 2007; Wani et al., 2008) [28,58] .

Measures to promote uptake of conservation practices include:

1. Participatory research and demonstrations on suitability of conservation methods in specific farming systems. Farmers need enough time to test out new technologies before they adopt them. 2. Emphasis on rain water management and soil conservation for short term and long term benefits. 3. Provision of tools and infrastructure: if BBF systems are recommended, adequate equipment for planting and construction should be provided. 4. Farmer-to-farmer knowledge transfer by means of field demonstrations, peer interactions and experience sharing so as to accelerate adoption and reduce perceived risk. 5. Government policy support: in China, terracing has been promoted through subsidies; in India, contour bunding was actively promoted between 1974 and 1989. 6. Awareness campaigns on environmental problems such as soil erosion and water inefficiency and their on-site and off-site consequences. 7. Risk reduction: Farmers are more likely to adopt technologies that reduce uncertainty. Prioritise low-risk SWC practices. 8. Integration with watershed programmes for enhanced impact and collective management.

Future Perspectives and Research Gaps

Future research should focus on long-term site-specific assessments of SWC practices, integration with digital and precision technologies, and comprehensive assessments of

Conclusion

Soil and water conservation practices are vital for increasing productivity, resilience and sustainability of dryland farming systems in the face of mounting climate variability. The combined application of conservation tillage, mulching, contour farming, land configuration, cover cropping and agroforestry in situ is effective to improve rainfall use efficiency, soil moisture retention and soil health to stabilize crop yields. Watershed based approaches, check dams, percolation structures, rainwater harvesting and microirrigation are complementary ex-situ interventions which further increase water availability during critical growth stages and mitigate land degradation. The new comparative effectiveness analysis (Table 3) confirms the contextdependent nature of optimal practice selection and the superiority of a mixed in-situ and ex-situ approach over single-practice approaches. Despite this evidence base, wider adoption is constrained by socio-economic, knowledge-based and site-specific barriers including inadequate attention to gender equity and policy alignment. Therefore, location specific participatory and policy supported SWC strategies are needed for sustainable intensification and climate resilient dryland agriculture. Future research should be directed

Acknowledgement

towards systematic comparative studies, long-term carbon accounting and gender-inclusive technology transfer frameworks.

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