Treated wastewater irrigation, Bajra Napier hybrid grass, green fodder yield, dry fodder yield, crude protein, crude fibre.

Agriculture and livestock production form a symbiotic relationship crucial for comprehensive food security. In India, livestock production significantly contributes to the national economy, accounting for 5.1% of the total national value added at current prices in 2018-19 (BAHS, 2019). While India leads globally in milk production, producing 198 million tonnes, the per capita output remains low due to severe feedstuff shortages (Rapiya et al., 2025). This paradox highlights the pressing need for improved fodder management and production strategies. The disparity between livestock population and available resources in India is stark. Despite occupying only 2.0% of the global geographical area, India supports 15% of the world's livestock population, indicating intense pressure on the country's resources (Singh et al., 2022). This imbalance is further exacerbated by the insufficient cultivation of feed crops, with only 8.4 million hectares dedicated to this purpose (Mohan et al., 2017). Moreover, the available green forage meets merely 40% of the required amount. Addressing this substantial gap in fodder availability is crucial for sustaining and enhancing livestock productivity, which in turn is vital for maintaining food security and economic stability in the agricultural sector (Hasnain et al., 2023).

The agricultural sector in India faces significant challenges regarding water allocation and usage. While it remains the largest consumer of water resources, projections indicate a 10-15% reduction in irrigation water allocation over the next two decades (CWC, 2019). This shift occurs against the backdrop of India's total utilizable water resources, estimated at 1,122 billion cubic meters per year (BCM/year), comprising 690 BCM of surface water (CGWB, 2019) and 432 BCM of groundwater (MoWS, 2017). Looking ahead to 2050, estimates suggest a total available water supply of 1,180 BCM under a high projection scenario, with irrigation still accounting for the majority (68%) of usage, followed by domestic use (9.5%), industries (7%), power development (6%), and other activities including evaporation losses, environmental needs, and navigation requirements (9.5%) (Elmahdi, 2024). The changing landscape of water demand and allocation presents both challenges and opportunities for India's water management strategies. While agricultural water use is expected to decrease by 10-12% by 2025, overall water demand is projected to increase by 22% in 2025 and 32% by 2050 (Amerasinghe et al., 2013). This shift in water allocation patterns underscores the need for more efficient water use practices, particularly in the agricultural sector (Ahmad et al., 2023). Additionally, the issue of water contamination remains a pressing concern, with a majority (80%) of wastewater being released into water bodies with little to no treatment. Only a small percentage of wastewater undergoes partial or complete treatment before discharge (14% in Indonesia, 10% in Philippines, 24% in India, and 4% in Vietnam), highlighting the urgent need for improved wastewater management and treatment infrastructure to address water quality issues in emerging countries like India(Rastogi et al., 2024).

The increasing demand for water across various sectors, including domestic use, industrial applications, and agricultural operations, has led to a growing interest in wastewater regeneration (Denora et al., 2023). This approach offers a cost-effective and attractive solution for crop irrigation, particularly in arid and semi-arid regions where maintaining productivity is challenging (Sharma et al., 2014; Zahmatkesh et al., 2022). Water reclamation and reuse have emerged as the most efficient methods to address both current and future water requirements. In this context, the utilization of treated wastewater for irrigating fodder crops presents a viable option in the evolving landscape of water demand management. The implicit research gap is the lack of comprehensive studies specifically evaluating the combined long-term impact of treated wastewater with integrated organic and inorganic nutrient management on both the yield and detailed proximate parameters (quality) of Bajra Napier hybrid grass in a specific agro-climatic zone like the Cauvery Delta. While individual components might have been studied, the synergistic interaction and its effect on both quantitative (yield) and qualitative (proximate parameters) aspects over extended periods are less explored, particularly with an emphasis on sustainable practices and resource conservation.

The study aims to fill the gap of how these specific combinations affect this particular fodder crop's yield and quality under the given regional conditions, contributing to the broader goal of conserving groundwater and utilizing available nutrients in treated wastewater effectively. The studies conducted in the Cauvery Delta region of Orathanadu, Thanjavur, Tamil Nadu, aimed to investigate the impact of secondary treated wastewater irrigation, manure, and inorganic fertilizers on the Bajra Napier hybrid grass variety CO(BN) 5. This research focused on assessing the effects of these treatments on fodder yields and proximate parameters of the grass. By examining the potential benefits of using treated wastewater for irrigation in combination with different fertilizer types, the study sought to contribute valuable insights into sustainable agricultural practices and water resource management in the region.

A. Site description 

Orathanadu is one of the leading agriculture production areas under the old Cauvery delta irrigation scheme of Thanjavur, Tamil Nadu, India. Rice, greengram, blackgram, sesame, sugarcane and coconut are the major crops and dairy, sheep and goats are central livestock units. Orathanadu belongs to town panchayat with a population of 1.60 lakhs (2011 census) and 40,383 residents consume an average of 14.2 lakh litres of water every day. The outlet wastewater from households was collected by Orathanadu town panchayat, Tamil Nadu. The secondary treated wastewater was supplied to the Veterinary College and Research Institute, Orathanadu. In this college, the secondary treated wastewater is utilized for cultivating fodder crops, especially Bajra Napier hybrid grass and multicut sorghum. This treated wastewater was utilized for irrigation purposes for the experimental study to cultivate the Bajra Napier (Pennisetum americanum x P. purpureum) hybrid grass. The study area has a semi-arid climate, with less than 792 mm of annual rainfall and summer temperatures often exceeding 40.4⁰C. The soil of the experimental field is sandy clay loam in texture and coarse sand (41.63%) was the dominant constituent with an infiltration rate of 3.06 cm hr-1. The experimental site's soil bulk density is 1.42 g cm-3 and a particle density of 2.98 g cm-3.

B. Experimental design   

Field experiment was laid out in a strip plot design with four replications on a total of 80 plots, each of 6.0 m length and 4.5 m width. The gross plot size was 27 m2  with 2 m space between the plots to avoid the influence of water seepage. Five ratios of irrigation water were used as horizontal factor treatments, viz., I1 - Groundwater alone (GW), I2 - Alternate irrigation with GW and treated wastewater (TWW), I3 - Two irrigations with GW + one irrigation with TWW, I4 - One irrigation with GW + two irrigations with TWW and I5 - Irrigation with TWW alone and in vertical factors, nutrients viz., N1 - 100% Inorganic nutrients (IN), N2 - 100% Organic nutrients (ON) on N basis, N3 - 50% Organic + 50% Inorganic nutrients and N4 - Control (without nutrients). Perennial fodder crop Bajra Napier hybrid grass variety CO(BN) 5 was cultivated for experimental purposes.

C. Cultivation practices and fertilizer application 

The fodder crop Bajra Napier hybrid grass CO(BN)-5 was planted with two budded setts on 28th December 2018, with a spacing of 0.60 m between rows and 0.50 m between plants. The nutrient treatments were imposed after calculating the doses at the time of planting. Fertilizers and manure were applied through broadcasting to the individual plots and mixed manually. Nitrogen, phosphorus and potassium were applied as urea, single super phosphate and muriate of potash, respectively. In addition, organic manure in the form of farmyard manure was applied. After every harvest, the ratoon crop was applied with nitrogen as top-dressing as per the treatments. The details of the nutrient application are furnished in Table 1. 

Table 1: Manure and fertilizers applied to the experimental field.

D. Yield and proximate analysis 

The main crop was harvested at 70 days after planting (DAP). The succeeding six ratoon crops were harvested at 45 days intervals. The green and dry fodder yields (t ha−1) of the main crop and six ratoon crops were recorded at harvesting time and presented in total green and dry fodder yields (t ha−1 yr−1). In addition, the plant samples from each treatment in each harvest were also collected. These samples were dried and subjected to proximate analysis viz., crude protein and crude fibre. 

E. Statistical analysis 

All the data obtained from the treatment plots and proximate parameters were analyzed in the lab and were subjected to a statistical analysis using analysis of variance (ANOVA). The least significant difference (LSD) at the probability of 5 % (P<0.05) was performed to compare means using SPSS for Windows (Released version 26) according to the standard methods (Gomez and Gomez 2010)

A. Green and dry fodder yields 

The effect of treated wastewater irrigation, manure and inorganic nutrients and thier interaction differed significantly (P<0.05) on green and dry fodder yields (Table 2 and 3) of Bajra Napier hybrid grass. The irrigation with treated wastewater alone (I5) produced significantly higher total green fodder yield of 383.8 t ha−1yr−1 than all other irrigation treatments and it was on par with one irrigation with groundwater and two irrigations with treated wastewater (I4). This might be due to the fact that, the application of treated wastewater as irrigation throughout the cropping period provides an important source of plant nutrients, especially nitrogen and mineralisation of organic matter, which can increase forage crop growth and yield. Since, Bajra Napier hybrid grass is a C4 plant which has a higher photosynthetic nitrogen usage efficiency (NUE) than C3 plants it can metabolise high nitrogen levels in reclaimed water (Alkhamisi et al., 2011). Similar results were obtained in sorghum, bajra napier and barley crops (Galavi et al., 2009; Srinivas et al., 2014). The lowest total green fodder yield (278.0 t ha−1 yr−1) was registered in the control (irrigation with groundwater alone - I1).

Among the nutrient management, 100% inorganic nutrients (N1) observed a higher total green fodder yield of 408.3 t ha−1 yr−1 than other treatments and control (267.5 t ha−1 yr−1). The favourable growth parameters might be attributed to the increase in green fodder production under recommended doses of manure and inorganic fertilizers application (Bhardwaj et al., 2021). Presence of nitrogen might have promoted cell division and as a result, internode elongation and in turn, overall growth parameters (Sharma et al., 2022). The results were in accordance with other researchers (Gori et al., 2004; Kaur et al., 2017; Keshav Prasad Kurmi et al., 2023).

The interaction effect of secondary treated wastewater irrigation and inorganic nutrient treatments revealed that, the treated wastewater alone and 100% inorganic nutrients (I5N1) recorded significantly more total green fodder yield (431.1 t ha−1 yr−1) than irrigation with GW alone without nutrients (222.6 t ha−1yr−1). The amount of N, P and K deposited in the soil was proportional to the amount of wastewater used in irrigation and the quantity of inorganic nutrients applied. As a result, it promoted more extensive crop growth and increased forage yield. The wastewater contains essential nutrients for plant growth, such as N, P and K, as well as micronutrients like iron (Fe), zinc (Zn), manganese (Mn) and copper (Cu) as well as a significant amount of organic matter (Senthilkumar et al., 2021). Furthermore, N is an essential constituent of amino acids and chloroplasts, which directly influence plant leaf area, growth and development through greater photosynthates, resulting in higher green fodder yield, which may be attributed to the addition of irrigation at optimum soil moisture and nutrients. These findings align with what has previously been published by Nogueira et al. (2013); Alghobar and Suresha (2016); Ghassemisahebi et al. (2020).

Table 2: Effect of treated wastewater and nutrients on total green fodder yield (t ha-1yr-1) of Bajra Napier hybrid grass.

A similar trend was seen in dry fodder yield also. The total dry fodder yields (total of all crop harvests from main and six ratoons) expressed significant (P<0.05) differences by using treated wastewater for irrigation along with manure and inorganic nutrients (Table 3). Among the different irrigation treatments, irrigation with treated wastewater alone (I5) produced significantly higher total dry fodder yield of 69.12 t ha−1 yr-1 and the lowest total dry fodder yield was registered in control (I1) which irrigated with groundwater alone (54.62 t ha−1 yr-1). The optimal soil-water, macro and micronutrient availability increases nutrient uptake resulting in increased growth parameters that influence dry fodder output. The results were on par with previous research works (Santos et al., 2014; Nogueria et al., 2013). 

In the manure and inorganic nutrient treatments, the plot applied with 100% inorganic nutrients (N1) showed significantly higher total dry fodder yield (72.45 t ha−1 yr-1) compared to all other nutrient treatments. Applying inorganic nutrients, especially nitrogen, increases the plant's leaf area. Under optimum nutrient level, with adequate sunlight, increased leaf area would increase the photosynthates and finally produces more dry fodder yield of the bajra napier hybrid grass. The application of manure that releases more nutrients slowly throughout the crop growth period also improves the higher dry fodder yield. Similar research findings were also reported earlier (Bandeswaran et al.,  2013; Khadijah, 2016; Utamy et al., 2018).

Table 3: Effect of treated wastewater and nutrients on total dry fodder yield (t ha-1 year-1) of Bajra Napier hybrid grass.

On interaction effect, treatment with treated wastewater alone and 100% inorganic nutrients (I5N1) recorded significantly were total dry fodder yield (76.72 t ha-1  yr-1) compared with all other treatment combinations and control (47.68 t ha−1 yr-1). The increase might be due to nutrients available in TWW,  the decomposition of organic manure being accompanied by a release of appreciable quantities of nutrients and higher mineralisation of full dose of fertilizers, which contribute to higher total dry fodder yield. The results of green fodder yield reflected in dry fodder yield too. Therefore, dry fodder yields under-treated wastewater with manure and fertilizer matches the previous results (Bharadwaj et al., 1994; Larson, 2010; Raveena et al., 2021).

B. Fodder quality parameters

The plant samples were collected during the harvest of the main and six ratoon crops and from all the treatment plots and used for proximate compound analysis. The important fodder quality parameters viz., crude protein and crude fibre contents, were analyzed and the average content of all harvests were presented.

C. Crude protein content 

The protein content of forage crops is an important quality factor from the animal nutrition point of view. The crude protein content is directly related to the nitrogen percentage of the plant tissue. Adopting irrigation with treated wastewater combined with organic and inorganic nutrients have shown significantly increase on the crude protein content of Bajra Napier hybrid grass (Table 4) and it’s ranged from 9.58-13.53 per cent. Among the treatments, irrigation with treated wastewater alone (I5) registered significantly higher average crude protein content (12.64%) than all other treatments. Control (irrigated with groundwater alone - I1) registered the lowest crude protein content (10.70 %). The increased crude protein content with treated wastewater might be due to the partial supply of nitrogen throughout the lifecycle of forage crop growth. The rise in crude protein content in corn fodder could be linked to sufficient nitrogen in wastewater (Tavassoli et al., 2010). Several studies have reported a significant increase in crude protein content of sorghum, maize and tomatoes through the application of treated wastewater as irrigation source (Ghanbari et al., 2007; Galavi et al., 2010; Orlofsky et al., 2016).

Table 4: Effect of treated wastewater and nutrients on mean crude protein (%) of Bajra Napier hybrid grass.

Mean data (Table  4) of all seven crop harvests (from the main crop to sixth ratoon harvest) in a year influenced by manure and inorganic nutrient application significantly. The treatment applied with 100% inorganic nutrients (N1) registered significantly greater crude protein content (13.16%) than all other treatments and the control. This could be due to adequate nitrogen application through manure and inorganic nutrients increased the vegetative growth, N concentration, amino acids and protein content in forage, ultimately increased the total crude protein yield. In addition, the slow release of nitrogen in organic manure had an added advantage to uptake and increased the crude protein content in the bajra napier forage crop. The findings corroborate with the earlier findings (Vennila and Anathi 2019; Sheta et al., 2010), that reported increasing the crude protein content with the application of manure and inorganic nutrients. 

Among irrigation and inorganic nutrients combinations, treatment imposed with treated wastewater alone and 100% inorganic nutrients (I5N1) recorded significantly higher crude protein content (13.53%) than all other treatments. It could be because of the presence of numerous nutrients, particularly nitrogen, in treated wastewater which are required for the growth of bajra napier hybrid grass (Fig. 1). The availability of sufficient moisture and adequate nutrients favoured early canopy development, resulting in greater nutrient uptake, which promoted the synthesis of more metabolites and paved the way for higher crude protein yield. Also, higher use of solar radiation due to increased leaf N concentrations resulting from high N availability in the soil after adopting treated wastewater irrigation. As a result, the crude protein content reflected the nutrient concentration, particularly nitrogen. These findings were on par with other researchers (Mojid et al., 2012; Senthilkumar et al., 2021). 

Fig. 1. Effect of treated sewage water and nutrients on crude protein (%) of bajra napier hybrid grass.

D. Crude fibre content 

The total crude fibre content of the Bajra Napier hybrid grass is significantly affected by the use of treated wastewater for irrigation, manure and inorganic nutrients (Table 5).  Among different irrigation treatments, significantly lower crude fibre (28.80%) was seen in irrigation with treated wastewater alone (I5) than other treatments. The highest crude fibre content (30.36%) was recorded in control (I1 - irrigated with groundwater alone). This might be due to partial supplement of nitrogen in treated wastewater increased the photosynthates which reduce in turn the accumulation of cellulolytic components in plants and decreased the crude fibre content. On the other hand, there is no nutritive value in groundwater that induces lignin accumulation in the plant cell. These results were supported by other research findings (Raveena et al., 2021).

Table 5: Effect of treated wastewater and nutrients on mean crude fibre (%) of Bajra Napier hybrid grass.

Among the nutrient treatments, the plots received 100% organic nutrients (N1) received treatment registered significantly lower average crude fibre content (28.47%) compared to the control (30.51%) and other treatments. The value of crude fibre is an indirect indication of the digestibility of the forage. It is known that higher crude fibre content lowers the digestibility and vice-versa. The availability of nitrogen fraction in the soil through manure and inorganic nutrients might improve the carbohydrates and reduce the formation of lignin, cellulose and hemicellulose material, which are responsible for increasing the crude fibre content. The decrease in nitrogen content increases the crude fibre in observed by other scientific workers in bajra napier (Bandeswaran et al., 2013; Khadijah, 2016).  In interaction effects of irrigation and inorganic nutrients, combination of treated wastewater along with 100% inorganic nutrients (I5N1) recorded significantly lower crude fibre content (28.03%) than all other treatment combinations (Fig. 2). Lower fibre content in treated wastewater and inorganic nutrition applied treatment compared to the control could be due to the supply of sufficient essential nutrients and better decomposition of organic matter improved the availability of nutrients resulting in high succulent biomass formation and yield. The same results were reported earlier (Galavi et al., 2009; Raveena et al., 2021; Malarvizhi et al., 2001).

Fig. 2. Effect of treated sewage water and nutrients on crude fibre (%) of bajra napier hybrid grass.

Building upon these findings, future research should delve deeper into several critical areas to further enhance the sustainability and long-term viability of using treated wastewater for fodder production:

∙ Long-Term Environmental Monitoring: Conduct multi-year studies to assess the long-term impact of treated wastewater irrigation on soil health, including potential accumulation of heavy metals, emerging contaminants (e.g., pharmaceuticals, microplastics), and their effects on soil microbial communities and biodiversity.

∙ Fodder Safety and Livestock Health: Evaluate the uptake of potential contaminants from treated wastewater into the Bajra Napier hybrid grass and its subsequent transfer to livestock. This should involve feeding trials to determine any effects on animal health, productivity, and the safety of animal products (e.g., milk, meat).

∙ Optimizing Nutrient Recycling: Further investigate the precise nutrient contributions from different types of treated wastewater and organic manures to optimize inorganic fertilizer application rates, promoting greater nutrient use efficiency and reducing external inputs.

∙ Water Quality and Treatment Levels: Explore the impact of different levels of wastewater treatment (e.g., primary, secondary, tertiary) on fodder yield, quality, and environmental safety to identify the most cost-effective and environmentally sound treatment standards for agricultural reuse.

Senthilkumar D. and  M. Ramachandran (2025). Study the Integrated Effect of Treated Wastewater, Organic and Inorganic Nutrients on Fodder Yield and Proximate Parameters of Bajra Napier Hybrid Grass in the Cauvery Delta Region of Tamil Nadu. Biological Forum, 17(4): 117-125.