The results of study showing the impact of different organic mulch treatments on soil properties and nutrient availability are given in Table 1. In terms of soil temperature, the application of all three types of organic mulch contributed to maintaining a relatively moderate average temperature of around 27.3°C to 27.4°C, while the control treatment exhibited a significantly higher soil temperature of 41.6°C. The pH of the soil remained stable across all treatments, approximately at 7.9 to 8.1. One of the notable effects of the organic mulch treatments was on soil carbon content, which serves as an indicator of organic matter input. The application of wheat straw, rice straw, and sugarcane leaf straw mulches led to an increase in soil carbon content to 0.68%, 0.72%, and 0.70%, respectively. In contrast, the control treatment exhibited a lower soil carbon content of 0.51%, highlighting the potential of organic mulch in enriching the soil's organic matter content. Regarding nutrient availability, the organic mulch treatments demonstrated their beneficial impact. Available nitrogen levels increased in the presence of organic mulch, ranging from 0.045–0.049%, compared to the lower nitrogen availability of 0.028% in the control treatment. Similarly, the mulch treatments resulted in higher levels of available phosphorus (ranging from 6.4 mg kg− 1 to 6.5 mg kg− 1) and available potassium (ranging from 89 mg kg− 1 to 92 mg kg− 1) compared to the control treatment's lower values (5.6 mg kg− 1 for phosphorus and 71 mg kg− 1 for potassium). Furthermore, the application of organic mulch significantly increased soil organic matter content, with values ranging from 0.77–0.81%. In contrast, the control treatment exhibited a lower organic matter content of 0.51%.
Table 1
Effect of organic mulch on soil and its nutrients availability
Treatments | Soil temp. (°C) | Soil pH | Soil carbon (%) | N (% ) | P (mg kg− 1 ) | K (mg kg− 1 ) | Soil organic matter (%) | Weed population (m2) | Plant height (cm) | Bolls per plant | Open boll weight (g) | Seed-cotton yield (kg ha− 1) |
Wheat straw @ 5 tons ha− 1 | 27.4 a | 7.9 a | 0.68 a | 0.048 a | 6.50 a | 89 a | 0.78 a | 4 b | 145 a | 35 a | 3.10 a | 2743 a |
Rice straw @ 5 tons ha− 1 | 27.3 a | 7.9 a | 0.72 a | 0.045 a | 6.40 a | 92 a | 0.81 a | 4 b | 139 a | 33 a | 3.14 a | 2704 a |
Sugarcane leaf straw @ 5 tons ha− 1 | 27.4 a | 7.9 a | 0.70 a | 0.049 a | 6.43 a | 92 a | 0.77 a | 5 b | 142 a | 34 a | 3.12 a | 2713 a |
Control (no mulch) | 41.6 b | 8.1 a | 0.51 b | 0.028 b | 5.60 b | 71 b | 0.51 b | 23 a | 102 b | 29 b | 3.0 b | 2117 a |
LSD at 5% | 2.18 | ns | 0.11 | 0.008 | 0.35 | 5.47 | 0.10 | 1.34 | 12.45 | 2.13 | 0.082 | 63.72 |
The observed moderation of soil temperature through organic mulch application is of paramount significance. The ability of mulches to maintain a relatively stable average soil temperature (27.3°C to 27.4°C) is indicative of their role in regulating soil microclimates. Mulches act as a buffer against temperature and moisture fluctuations (Lal 2016), creating a more stable thermal environment conducive to the optimal growth and development of microorganisms and plants (Chen et al. 2014; Gao et al. 2022). By minimizing extreme temperature variations, mulches contribute to fostering favorable conditions for soil organisms, nutrient cycling, and root activity (El-Beltagi et al. 2022; Sun et al. 2022), ultimately enhancing overall agricultural productivity and sustainability.
The notable increase in soil carbon and organic matter content resulting from the application of wheat straw, rice straw, and sugarcane leaf straw mulches is indicative of enhanced organic matter input. This increase reflects improved organic matter input into the soil, which in turn has positive implications for soil health, carbon sequestration, water retention, and overall agricultural sustainability (Turmel et al. 2015). Organic mulches serve as a continuous source of organic matter, which enriches the soil with nutrients and promotes the growth of beneficial soil microorganisms (Bot and Benites 2005; Zhang et al. 2020). As the mulches gradually break down, they release essential nutrients that plants require for growth (Shaji et al. 2021). This influx of organic matter improves soil structure, porosity, and nutrient-holding capacity, resulting in healthier and more productive soils (Menzies Pluer et al. 2020). In addition, organic matter acts as a sponge, aiding in the absorption and retention of moisture during periods of rainfall or irrigation. This, in turn, mitigates water runoff, enhances soil structure, and augments the availability of water to plants during dry spells, contributing to enhanced drought resilience. The introduction of organic matter through mulches significantly boosts the soil's carbon content (Li et al. 2020). Sequestering carbon in the soil helps to mitigate climate change by removing carbon dioxide from the atmosphere and storing it in the soil, acting as a long-term carbon sink (Almaraz et al. 2023). A healthier soil ecosystem translates to better nutrient cycling and enhanced resistance to pest and disease pressures. The observed rise in available nitrogen, phosphorus, and potassium levels in the presence of organic mulch treatments highlights their role in enriching the soil with essential nutrients. As the mulches decompose, they release essential nutrients and organic compounds that nourish plants and foster microbial activity (Shaji et al. 2021). Thus use of organic mulch plays a pivotal role in enriching the nutrient content of the soil as shown in our study (Table 1), thereby supporting plant growth and development (Table 1).
The effects of organic mulch treatments on key aspects of cotton including weed population dynamics, cotton plant growth, boll production and yield-related traits are given in Table 1. The application of organic mulch treatments exhibited a noteworthy impact on weed population control. The wheat straw, rice straw, and sugarcane leaf straw treatments led to a remarkable reduction in weed density, with only 4 to 5 weeds per square meter. In contrast, the control treatment demonstrated a considerably higher weed population of 23 weeds m2, underscoring the weed-suppressive effect of organic mulch. The significant suppression of weed populations under organic mulch treatments is of paramount importance. The decline in weed population observed with the application of mulches can be attributed to their ability to suppress weed growth by intercepting sunlight necessary for photosynthesis (El-Beltagi et al. 2022). This shading effect disrupts the energy production and metabolic processes of weed plants (Singhal et al. 2020), curbing their growth and ultimately leading to a more favorable environment for cultivated crops. Cotton plant height was positively influenced by the organic mulch treatments. The plants in the wheat straw, rice straw, and sugarcane leaf straw treatments exhibited greater heights, ranging from 139 cm to 145 cm. Conversely, the control treatment resulted in shorter cotton plants, averaging at 102 cm in height. A substantial correlation was observed between organic mulch application and boll production. Cotton plants under the wheat straw, rice straw and sugarcane leaf straw treatments yielded higher numbers of bolls per plant (33 to 35 bolls per plant). In comparison, the control treatment displayed a lower boll count per plant, averaging 29 bolls. Furthermore, the effect of organic mulch extended to open boll weight, a crucial yield-related trait. Open bolls in the wheat straw, rice straw, and sugarcane leaf straw treatments exhibited similar weights, measuring approximately 3.10 g, 3.14 g, and 3.12 g, respectively while the lowest open-boll weight (3.0 g) was recorded in control treatment where mulch was not applied. Perhaps most significantly, organic mulch treatments yielded higher quantities of seed cotton. The application of wheat straw resulted in higher yield (2743 kg ha− 1) however non-significant difference with rice straw and sugarcane leaf straw treatments, which yielded 2704 kg ha− 1 and 2713 kg ha− 1, respectively. In contrast, the control treatment yielded 2117 kg ha− 1, highlighting the potential of organic mulch to enhance cotton yield. In terms of ginning out turn (Table 2), all treatments exhibited relatively consistent percentages, ranging from 36.62–37.2%. This aspect of yield processing showed no significant variations among the organic mulch treatments and the control treatment. Thus, the application of mulches has demonstrated a comprehensive positive impact on various key parameters of cotton such as plant height, number of bolls, open-boll weight and seed cotton yield. This improvement can be attributed to the cumulative effects of enhanced soil structure, moisture retention, and nutrient availability. As mulches gradually decompose, they contribute organic matter to the soil, fostering improved soil aeration and structure. This favorable soil environment promotes robust root development and overall plant growth, resulting in taller cotton plants. Moreover, the suppression of weeds ensures that cotton plants can fully capitalize on the available resources, resulting in improved crop performance (El-Beltagi et al. 2022). Thus, the overall improvement in cotton yield-related traits, such as boll count and open boll weight, attests to the positive influence of these treatments on cotton productivity (Zhang et al. 2020) that also enhanced the cotton quality parameters such as staple length and fiber uniformity index. Results showed that mulching reduced the frequency of irrigation and overall irrigation water quantity as compared to control treatment. The number of irrigations in the wheat straw, rice straw, and sugarcane leaf straw treatments received 7 irrigations, resulting in a total irrigation amount of 533 mm. In contrast, the control treatment received 9 irrigations, resulting in relatively higher total irrigation amount of 685 mm. Similarly, crop water use efficiency differed significantly in cotton. Notably, organic mulch treatments showcased distinct impacts on crop water use efficiency. The wheat straw, rice straw, and sugarcane leaf straw treatments yielded greater efficiencies ranging from 0.50 to 0.51 kg m− 3. In contrast, the control treatment displayed a comparatively lower efficiency value of water use efficiency (0.30 kg m− 3). This can be attributed to the protective layer created by the mulch on the soil surface. By forming this barrier, the mulch minimizes direct exposure of the soil to sunlight, wind, and other environmental factors (Shah and Wu 2020; Zheng et al. 2022). Consequently, the rate of evaporation from the soil is lowered. As the mulch layer prevents rapid moisture loss, the soil retains more water for extended periods (Prem et al. 2020). This diminished evaporation and prolonged moisture retention contribute to a decreased demand for frequent irrigation. The impact of organic mulch treatments on key aspects of cotton fiber quality, irrigation practices, and crop water use efficiency are given in Table 2. The length of cotton fibers, known as staple length, displayed minor variations among treatments. The wheat straw, rice straw, and sugarcane leaf straw treatments yielded staple lengths of 28.1 mm to 28.2 mm that was significantly higher than the staple lengths of control treatment, measuring 26.1 mm. Likewise, fiber fineness remained relatively uniform across all mulched treatments (4.2 µg/inch) and control treatment (4.3 µg/inch). Similarly, fiber uniformity index demonstrated minor fluctuations. The wheat straw, rice straw, and sugarcane leaf straw treatments showed the uniformity indices of 92% while the control treatment exhibited a slightly lower index of 89%. Fiber strength, a crucial determinant of cotton quality, appeared consistent across treatments.
Table 2
Effect of organic mulch on quality of cotton, number of irrigations, total irrigation amount and crop water use efficiency
Treatments | Ginning out turn (%) | Staple length (mm) | Fiber fineness (µg/inch) | Fiber uniformity index (%) | Fiber strength (tppsi) | No. of irrigations | Total irrigation water (mm) | Crop water use efficiency (kg m− 3) |
Wheat straw @ 5 tons ha− 1 | 37.2 a | 28.1 a | 4.2 | 92 a | 93.2 a | 7 b | 533 b | 0.51 a |
Rice straw @ 5 tons ha− 1 | 37.1 a | 28.2 a | 4.2 | 91 a | 93.1 a | 7 b | 533 b | 0.50 a |
Sugarcane leaf straw @ 5 tons ha− 1 | 37.2 a | 28.1 a | 4.3 | 92 a | 93.2 a | 7 b | 533 b | 0.50 a |
Control (no mulch) | 36.6 b | 26.1 b | 4.3 | 89 b | 93.1 a | 9 a | 685 a | 0.30 b |
LSD at 5% | 0.32 | 0.75 | ns | 0.76 | ns | 0.45 | 34.10 | 0.09 |