Abstract
Ravines represent an extreme form of land degradation. Soil and moisture
saving techniques (SMSTs) have been identified as effective strategies
for improving the fertility of degraded lands. Three SMSTs viz.,
intercrop of cow pea and castor on bench terrace (SCCBT) ii) bench
terrace (SBT) iii) staggered trenches on natural slope (SSTS) and iv)
sapota on natural slope (Control) were imposed to observe their impact
on Sapota yield and quality, runoff, soil loss, and soil properties
under rain-fed conditions during 2018-20. SMSTs have significantly
affected plant growth, yield and quality and soil loss-runoff in
degraded ravines. The highest tree height was observed in SBT on par
with SCCBT and SSTS, and lowest in SS. Similar trend was observed in
case canopy spread, canopy volume and collar diameter. Among the
treatments, SCCBT recorded highest yield (38.3 kg
tree-1) followed by SBT, SST and lowest in SS (16.8 kg
tree-1). Pulp weight (55.55 g) and vitamin C (14.69
mg) was recorded higher in SCCBT and lowest in SS. SCCBT treatment
reduced runoff by 44% and it was highest in SS. Despite this SCCBT
exhibited significant higher soil loss. Terracing and trenches exhibited
remarkable effect on EC, SOC, available major nutrients (NPK) compared
to control. SCCBT and SBT treatments significantly had higher soil
moisture (%) compare to control. Hence, the cultivation of sapota after
implementing terracing and staggered trenches on natural slopes proves
to be a viable approach for effectively utilizing degraded ravines while
promoting productivity.
Key words: Bench terraces, canopy volume, fruit quality, runoff, soil
loss, soil nutrients, ravines Introduction
Ravines are often considered to be one of the most degraded forms of
landscapes in drylands. In India, an estimated 4.32 M ha of land is
affected by ravines (Kar et al., 2009). They are formed by water erosion
that imparts soil erosion, nutrient depletion, eventually declined soil
fertility and moisture retention. Stream bank erosion is one of the
prime sources of land degradation in ravine areas. This erosion
deteriorates drainage systems, which ultimately results in natural
catastrophe such as floods, and non-point source pollution in the
affected areas. Improper land use practices such as over-cultivation,
tillage, and land clearance can disturb the soil structure and make the
land prone soil erosion (MartÃnez-Hernández et al., 2017). Illicit
mining activities can lead to the removal of green cover and
destabilization of slopes, resulting in increased soil erosion rates
(Sahu & Dash, 2011). Uncontrolled grazing can also cause soil
compaction and trampling, which can damage vegetation cover and expose
the soil to erosion (Sharma, 1997; Rodrigo-Comino et al., 2017).
Deforestation is another major cause of soil erosion, as it can remove
the protective cover provided by trees and vegetation (Keesstra, 2007;
Sikka et al., 2016). Land use change, such as transformation of natural
forests or grasslands to agricultural land, can also contribute to
increased soil erosion rates (Navar & Synnott, 2000).
Soil erosion lead to the loss of surface-top soil, which is rich in SOM
and essential nutrients, are indispensable for plant growth (Jinger &
Kakade, 2019). It also changes soil texture, structure, and nutrient
content, which can further affect plant growth and ecosystem function.
These changes have long-term impacts on soil fertility, and soil
degradation thereby. Consequently, results in reduced plant growth, crop
productivity and fruit quality, and can alter the structure and function
of ecosystems (Lal, 2001; Atucha et al., 2013). Nutrient and moisture
deficit, soil compaction, and high summer temperatures further
negatively affect plant growth and crop productivity in ravines. In
addition, biotic stressors such as pest and diseases also reduce crop
yields in these areas (Jinger et al., 2022). Therefore, vegetation in
ravine lands faces multiple stresses both biotic and abiotic.
Combination of stress events can create an uneconomical and challenging
environment for farmers practicing agriculture in ravine lands. Further,
effects of climatic variability, such as increased rainfall and its
intensity, further exacerbate soil erosion rates in many areas including
ravines, leading to additional challenges for farmers and communities
(Adams et al., 2020; Blenkinsop et al., 2021; Tabari, 2020). In
addition, changes in temperature and precipitation patterns can also
affect vegetation growth and post monsoon soil moisture availability.
This could have significant implications for global food security, as
erosion can lead to reduced crop yields and soil degradation. Soil
degradation, including erosion, exerts a detrimental influence on the
growth of plants, their yield, and the quality of their fruits (Prakash
et al., 2011; Jinger et al., 2023). Panigrahi et al., (2017) reported
reduction in yield and productivity of mandarin on lands having 12%
slopes under water stress areas. Therefore, enhancing productivity of
such lands under changing climatic scenarios would pose serious
challenges.
Soil and moisture saving techniques (SMSTs) such as bunding, terracing,
trenches, and in situ water conservation etc. found potent in
enhancing the productivity of ravines and improving their climate
resilience (Kurothe et al., 2014). Panigrahi, et al. (2009) reported
that continuous bunding, continuous trenching, and staggered trenching
between rows helpful in minimizing runoff, soil loss, and nutrient loss,
while enhancing growth, yield, and fruit quality of Nagpur mandarin
grown in sloppy lands under drought prone areas. These measures assist
in saving precious soil and water resources, improving soil quality by
conserving moisture and nutrient rich top soils (Dagnachew et al., 2020;
Kumar et al., 2020a; Moradi et al., 2014). Studies have shown that SMSTs
are proven to mitigate surface runoff, soil and nutrients loss, and to
improve vegetative growth, yield, and fruit quality (Liu et al., 2012;
Mahajan et al., 2021; Moradi et al., 2014; Jinger et al., 2023).
However, there is a lack of extensive research focusing on the potential
of resilient perennial fruit crops and SMSTs to enhance productivity in
degraded ravines, while also improving the yield and quality of fruit
crops in erosion-prone areas in sustainable manner. Existing studies
have identified certain fruit crops suitable for marginal lands near
ravines, but they have not specifically addressed the challenges faced
by ravine slopes in rain-fed environments (Parandiyal et al., 2018;
Kumar et al., 2020c). As a result, the potential of hardy perennial
fruit crops and SMSTs remains largely unexplored on a large scale for
ravine slopes, primarily due to the adverse conditions found in these
areas. Implementation of technologies which are sustainable under these
situations, have less water and nutrient demands, and potential to
conserve resources like water, nutrients, and soil will provide
satisfying assurance to improve the productivity and impart substitute
source of remuneration to the farmers in ravines. Moreover, it is
crucial to promptly identify suitable crops and SMSTs for ravine lands.
Failure to address these issues may result in the encroachment of
fertile and cultivable lands by ravine heads.
Sapota (Manilkara zapota L.) is hardy, perennial fruit crop
having good adaptation capacity to various abiotic stresses. Increased
leaf succulence, accumulation of compatible solutes, and strong root
distribution makes sapota better choice different agro-ecological
regions. Therefore, it flourishes well from semi-arid tropics with
scanty rainfall to humid coastal regions (Rahman et al., 2019). Presence
of latex and tannins in leaves and fruits makes sapota less preferred
choice to wild animals. Therefore, bringing degraded ravines under
cultivation of sapota with the advantages of SMSTs will help to reduce
adverse impact of harsh conditions on crop growth, while improving the
productivity and resilience. With this background, following objectives
were set to explore the effectiveness of SMSTs in sapota.
To determine the impact of SMSTs on plant growth, fruit yield and
quality of rainfed sapota grown in ravines.
To assess the effectiveness of SMSTs on soil erosion, runoff loss,
soil fertility and post monsoon moisture status.