Effect of different phytomulches on soil and plant nutrients

Introduction

The mulberry (Morus spp.) leaf is a perennial plant with deep roots that is the only food source for the silkworm Bombyx mori L. The grade of silk produced is directly correlated with leaf quality. Additionally, the quality of mulberry leaves alone accounts for roughly 38.2% of the silkworm crop's success (Miyashita, 1986) [16] . However, the general condition of the soil also affects leaf yield and quality. Mulberry plantations in rainfed temperate locations frequently experience moisture stress, variable nutrient availability, and low soil organic matter. These limitations affect not only the nutrient status of the soil but also key biochemical traits of the leaf such as chlorophyll, protein, carbohydrates and fibre content. Since these parameters influence feeding efficiency, digestion and cocoon formation, improving both soil conditions and leaf composition remains a central requirement in mulberry cultivation. Mulching with plant-based materials has emerged as a simple and sustainable method to enhance soil fertility and leaf quality. Plant based/phyto-mulches help to conserve moisture, moderate soil temperature, reduce weed competition and gradually enrich the soil as they decompose. These changes can influence important soil parameters such as organic carbon, available nitrogen, phosphorus and potassium (Singh and Chamroy, 2025) [25] , which in turn shape the physiological and nutritional profile of mulberry leaves. Improved nutrient availability often leads to higher chlorophyll formation, better protein synthesis, increased carbohydrate accumulation and favourable changes in crude fibre levels. Likewise, leaf nitrogen, phosphorus and potassium concentration reflects how effectively the plant absorbs nutrients from the soil. Although a variety of mulches, including paddy straw, dried weeds, leaf litter, sawdust, and aquatic weeds, are frequently used in field crops and orchards (Ganie et al., 2025) [13] , little is known about how particular phytomulches impact the entire range of soil and leaf parameters in mulberries grown in temperate climates.

It is crucial to comprehend this relationship because silkworm growth and cocoon productivity can be greatly impacted by even little changes in soil nutrients or leaf biochemistry. In this context, the present study evaluates the effect of seven phytomulches viz., paddy straw, dried weeds, wood chaff, dried leaves, aquatic weeds, Typha and sawdust on a comprehensive set of soil and leaf parameters. The study assesses soil organic carbon, available nitrogen, phosphorus and potassium, along with key mulberry leaf attributes including total chlorophyll, total protein, total carbohydrates, crude fibre and leaf NPK concentrations during spring and autumn seasons. The objective is to identify the phytomulch that most effectively enhances soil fertility and improves the biochemical and nutrient profile of mulberry leaves, thereby supporting better silkworm performance and sustainable sericulture.

Material and Methods

The study was carried out in the fall of 2022 The method outlined by Bremner (1965) [7] was used to assess the amount of accessible nitrogen. While the available potassium was measured using a flame photometer (Jackson, 1973) [14] , the available phosphorus was approximated using the method of Olsen et al. (1954) [18] .  Soil Organic Carbon (%): Walkley and Black's (1934) [27] quick titration method was used to quantify the soil organic carbon content.

 Total Chlorophyll (mg/g fw): Sadasivam and Manickam's (1992) [23] technique was used to calculate the total chlorophyll content.  Total Protein (%): According to Ranganna (1997) [21] ,

the Kjeldhal technique was used to calculate the total protein content.  Total Carbohydrate (%): According to Dubois et al.

(1956) [10] , the Phenol-Sulphuric acid method was used to calculate the total carbs.  NPK (%) of leaves: Jackson (1973) [14] outlined Microkjaldal's method for determining nitrogen (Plate-2). The Vandomolybedate phosphoric acid yellow color method was used to measure phosphorus (Jackson, 1973) [14] . According to Jackson's (1973) [14] protocol, potassium was measured using a flame photometer (Plate-3).  Crude fiber (%): The ceramic fiber filter method was used to estimate crude fiber.

Results

The observations recorded on various parameters are described hereunder in brief:

Soil Nitrogen (Kg/ha) Although T 6 (Typha) had the highest soil nitrogen content in the spring and autumn (338.74 kg/ha and 273.59 kg/ha, respectively), it was statistically comparable to T 1 (Paddy Straw), which had soil nitrogen content of 337.64 kg/ha and 272.21 kg/ha, respectively. In the spring and fall seasons, Control had the lowest soil nitrogen level of 320.71 and 259.47 kilos per hectare, respectively. The results are presented in Table 1 and illustrated in Figure 1.

In T 6 (Typha), soil phosphorus reached a high of 22.36 kg/ha and 18.39 kg/ha in the spring and fall, respectively. This was statistically comparable to 22.14 kg/ha and 17.72 kg/ha in T 1 (Paddy Straw). In both seasons, Control had the lowest soil phosphorus level (17.87 kg/ha and 14.02 kg/ha, respectively). The findings are presented in Table 1 and illustrated in Figure 2.

According to the study, applying phytomulches raises the potassium level of the soil. In comparison to the other treatments, T 6 (Typha) had the greatest (187.56 kg/ha in the spring and 150.41 kg/ha in the autumn). In T 1 (Paddy Straw), it was followed by 185.09 and 148.56 kg per hectare in the spring and fall, respectively. T 8 (Control) had the lowest potassium concentration, measuring 174.56 kg/ha in the spring and 138.03 kg/ha in the fall. The outcomes are shown in Figure 3 and provided in Table 1.

Soil organic carbon was highest (1.823%) in T 6 (Typha) during the spring season. It was statistically comparable to 1.700% in T 1 (Paddy Straw) and much higher than the other treatments, which varied from 1.187% in Control to 1.550% in T 2 (Dried Weeds). A similar pattern was seen in the fall, with T 6 (Typha) having the highest organic carbon content (1.947%), which was substantially greater than the other treatments but statistically comparable to 1.880% in T 1 7.

In T 8 (Control), the crude fiber content of the leaf was 11.60 and 11.86 percent in the spring and fall, respectively, and was considerably decreased by the application of phytomulches. In T 6 (Typha), it was the lowest (9.27 and 9.53 percent, respectively, in spring and autumn). In the remaining treatments, it varied from 11.33 and 11.62 in T 5 (Aquatic Weeds) to 9.51 and 9.74 percent in spring and autumn in T 1 (Paddy Straw). The outcomes are shown in Figure 8 and provided in Table 3.

In comparison to the other treatments, T 6 (Typha) had the highest nitrogen concentration (3.912%) during the spring. T 8 (Control) had the lowest nitrogen concentration (3.553%). In the fall, T 6 (Typha) had the highest nitrogen content (3.511%), which was substantially greater than the other treatments and statistically comparable to 3.474% in T 1 (Paddy Straw). T 8 (Control) also had the lowest nitrogen concentration (3.111%). The outcomes are shown in Figure 9 and provided in Table 3.

In the spring, T 6 (Typha) had the greatest phosphorus concentration (0.292%), which was statistically comparable to 0.285% in T 1 (Paddy Straw). At 0.218 percent, T 8 (Control) had the lowest phosphorus concentration. In the fall, T 6 (Typha) once more recorded the highest phosphorus concentration of 0.218 percent, which was quite comparable to T 1 (Paddy Straw)'s 0.205 percent. Again, T 8 (Control) had the lowest phosphorus concentration (0.150%). The results are shown in Figure 10 and provided in Table 3.

In the spring, T 6 (Typha) had the highest potassium concentration (1.896%), which was statistically comparable to 1.856% in T 1 (Paddy Straw) and 1.785% in T 2 (Dried Weeds). The other treatments had values of 1.729 (sawdust), 1.663 (dried leaves), 1.652 (wood chaff), 1.593 (aquatic weeds), and 1.555 percent (control). In the fall, T 6 (Typha) once again had the greatest potassium content (1.515%), which was statistically comparable to Paddy Straw (1.440%) and Dried Weeds (1.424%) and much higher than the other treatments, which varied from 1.031 in T 8 (Control) to 1.290%. Table 3 provides the results, which are shown in Figure 11.

Discussion

The observations recorded during the study are discussed here under:

Soil nutrients

Organic carbon is an indicator of health status of soil as it influences the soil physico-chemical and biological properties and is also the indispensible component of the soil system. The application of various organic mulches had a positive impact on the organic carbon content, with T 6 (Typha) having the highest (Spring: 1.823%; Autumn: 1.947%) and T 8 (Control) having the lowest (Spring: 1.700%; Autumn: 1.880%). Acharya et al. (1998) [1] , Balaji (1994) [5] , and Tindall et al. (1991) [26] also noted an increase in soil organic carbon content under various mulches compared to control. The degradation of mulches, increased microbial activity, improved soil moisture, and decreased carbon loss could all contribute to the rise in soil organic carbon under various organic mulches (Bajoriene et al., 2013) [3] . Although there were notable variations amongst the various phytomulches, the application of phytomulches also improved the NPK level in the soil. [20] , who found that mulching the soil with turf grass and green waste compost increased its NPK content compared to bare soil. Additionally, Bakshi et al. (2015) [4] found that soil NPK content improved under various organic mulches, such as forest leaves, paddy straw, and paddy husk, as compared to no mulch (Control). Higher organic carbon contents, improved soil moisture and warmth, and effective weed management could all contribute to the rise in soil NPK concentration. Adequate moisture ensures the uniform distribution of nutrients, preventing their accumulation or leaching. Further soil moisture affects the solubility and mobility of nutrients within the soil profile (Reisig, 2023) [22] .

Biochemical constituents

According to Murthy et al. (2013) [17] , the amount of chlorophyll in a plant is crucial for assessing its photosynthetic efficiency and foliage quality. Using phytomulches increased the total amount of chlorophyll. T 6 (Typha) had the greatest (Spring: 3.913 mg/g; Autum: 3.213 mg/g) and T 8 (Control) had the lowest (Spring: 3.452 mg/g; Autum: 2.747 mg/g). The results are consistent with those of Fan et al. (2021) [11] , who found that applying various organic mulches increased the amount of chlorophyll in Dendrocalamus latiflorus Munro leaves. Cozzolino et al.

(2020) [9] also showed similar outcomes with lettuce. Proteins perform diverse enzymatic, structural and functional role in plants, including processes such as photosynthesis and biosynthesis. For silkworm larvae, leaf protein is a crucial factor in determining the quality of their diet. Mulberry leaf protein is immediately biosynthesized to provide around 70% of the protein in raw silk (Bose et al., 1991) [6] . Most cells use carbohydrates as an instant energy source, however in many photosynthetic species, a large amount of carbohydrates are used for the synthesis of storage goods like starch or for the formation of structural elements like cellulose in cell walls. Sugars are essential macromolecules that provide cells with energy and are essential for both primary and secondary metabolism. The total protein content (Spring: 24.45%; Autumn: 21.94%) and total carbohydrate content (Spring: 9.189%; Autumn: 8.307%) was the highest in T 6 (Typha) while as the values were the lowest-total protein (Spring: 22.21%; Autumn: 19.44%) and total carbohydrate content (Spring: 8.413%; Autumn: 7.197%) in T 8 (Control). The findings of the study are supported by Pinjari (2007) [19] who also reported increase in protein and carbohydrate content in sweetcorn (Zea mays saccharata) mulched with polythene as against control. This improvement in total protein and carbohydrate content may be attributed to improved soil moisture, better nutrient uptake and efficient photosynthesis.

For silkworm growth, silk production, and general health, an ideal crude fiber content is essential. Mulberry leaf crude fiber content is significantly correlated with average filament length, silk productivity, shell weight, and shell percentage (Lohithashwa et al., 2024) [15] . The use of phytomulches considerably decreased the crude fiber content in leaves, which was highest in T 8 (Control) in the spring and fall at 11.60 and 11.86 percent, respectively. In T 6 (Typha), it was the lowest (9.27 and 9.53, respectively, in spring and autumn). The outcomes are consistent with the findings of Fan et al. (2019) [12] , who found that maize mulched with plastic, biodegradable material, and straw had less crude fiber than the control. Additionally, Awopegba et al. (2017) [2] found that mulches reduced the amount of fiber in maize. The rise in leaf moisture, protein, and carbohydrate content could be the cause of the decline in crude fiber content.

Leaf nutrient status

One essential nutrient needed for the best possible growth and development of plants is nitrogen (Salvagiotti et al., 2008) [24] . Photosynthesis, DNA synthesis, protein synthesis, respiration, and nitrogen fixation are only a few of the vital physiological activities in which it is crucial (Caliskan et al., 2008) [8] . Phosphorus is essential for photosynthesis, protein synthesis, seed germination, flowering, and bud development since it is a crucial part of biomolecules such nucleic acids, phospholipids, and coenzymes. In addition to boosting enzymatic activity and offering resistance to pests, diseases, frost, and other environmental challenges, potassium plays a major role in photosynthesis and water control. T 6 (Typha) had the highest leaf nitrogen content (Spring: 3.912%; Autumn: 3.511%) and T 8 (Control) had the lowest (Spring: 3.553%; Autumn: 3.111%). Similarly, T 6 (Typha) had the highest phosphorus content (Spring: 0.292%; Autumn: 0.218%) and T 8 (Control) had the lowest (Spring: 0.218%; Autumn: 0.150%) and T 6 (Control) had the highest leaf potassium content (Spring: 1.896%; Autumn: 1.555%; Autumn: 1.290%). The outcomes are consistent with those of Awopegba et al. (2017) [2] , who found that applying various mulches increased the nutrient content of maize. Similar findings were also reported by Bakshi et al. (2015) [4] , who discovered that using mulches increased the NPK content of Aonla (Emblica Officinalis Gaertn.) compared to the control. Their enhanced availability in the soil, control of soil temperature and moisture, microbial diversity, and decreased competition with weeds could all contribute to the enhancement in leaf NPK content.

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