Optimizing wheat growth and zinc uptake with compost and rice husk in alkaline conditions

Abstract

Background

Alkaline soils present significant challenges for sustainable agriculture, especially in regions where zinc deficiency limits both crop productivity and human nutrition. In this context, managing organic matter and micronutrient deficient soils is becoming a hot burning issue for the scientific community for ensuring both soil health and the food web. This study aims to investigate the potential impact of compost (CP), rice husk (RH), and zinc (Zn) amendments on zinc fortification in wheat (Triticum aestivum L.) cultivated in calcareous soils. The goal is to enhance the availability and uptake of zinc, thereby improving the nutritional quality of wheat grains. The experiment was conducted at the Ghazi University experimental farm, with eight treatments and three replicates. Each studied pot comprising 5 kg of sandy clay loam textured soil with “Akbar” variety of wheat as the test plant.

Results

The results of the study revealed highly significant improvements in all measured traits. The combined application of compost, rice husk, and zinc led to substantial increases in plant height (19.9%), spike length (59%), number of spikelet’s (36%), 1000-grain weight (24%), and grain zinc content (48.9%) compared to the control. Furthermore, significant enhancements in chlorophyll content, nitrogen, potassium, and zinc levels in the plant were estimated after Zn addition along with compost and rice husk.

Conclusion

The combination of RH with Zn exhibited the promising effects on wheat growth and yield. Moreover, the combined effect of RH and CP along with Zn expressed the highest performance in overall plant growth, increased soil organic matter, increased zinc concentrations in alkaline soil as well as in the grain of wheat. In addition, available phosphorus and potassium contents were also enhanced in zinc-deficient soil. This study provides the future directions to determine the effectual methods of Zn application for increasing the absorption and accumulation of Zn in wheat grains to address the human’s demand.

Introduction

Wheat (Triticum aestivum L.), often referred to as the “King of Cereals,” belongs to the Poaceae family and is the most widely cultivated cereal crop in the world. Globally, over 40% of the population relies on wheat as a staple food [1]. Wheat contributes nearly 55% of the total carbohydrate intake and 20% of the total calorie consumption worldwide [2]. It is recognized as crucial staple food among the Pakistani diets and is widely grown across the country. Pakistan is ranked at top the eighth-largest wheat producing countries of the world in terms of total production, yield per hectare, and area planted with wheat [3] According to the statistical report of Pakistan, total cultivated area of wheat was increased by 340 ha which accounts 26 Mt productions in 2022–2023 [4]. Wheat is a crucial agricultural commodity in Pakistan due to its significant involvement to state food security and economic constancy. Though, its grain production is prominently influencing through numerous biotic and abiotic factors. Among the abiotic limitations, nutrient imbalances and the deficiency in essential micronutrients are the major contributors to cause decline in its production [2]. Alkaline and calcareous nature soils in developing countries have led to decrease wheat productivity and quality, mainly due to the micronutrient deficiencies [5, 6].

Particularly, Pakistani soils are alkaline and calcareous in nature, leading to the reduced availability of certain nutrients due to factors such as high soil pH, excessive free Ca and CO³⁻ ions, lowest organic carbon contents, poor drainage, and uneven fertilizer use, are adversely affecting the mobility and bioavailability of essential micronutrients such as zinc (Zn), iron (Fe), and manganese (Mn), which impairing nutrient imbalances and damaging plant growth and development [7]. Zn plays a central role in supporting the normal growth and development of humans and animals, while its deficiency can lead to severe disorders in living organisms such as weakened brain and immune system efficiency, stunted growth, weakened disease resistance, adverse pregnancy outcomes, and increased morbidity and mortality [5]. In Pakistan, its deficiency affects 22.1% of women and 18.6% of young children, has strong contribution to inhibit the growth and development of 12 million children [3]. In addition, its deficiency is widely accepted as a major global health threat that led to cause malnutrition and more than 25% of the world’s population has been affected until now [8]. It serves as a key constituent in the structure of over 300 enzymes in the human body. It has potential to contribute in protein synthesis, DNA and RNA metabolism as well as the formation of proteins that are involved in gene expression, and the inhibition of free radicals [9]. However, its bioavailability declines in alkaline, carbonate-rich soils, due to fixation reactions, adsorption on calcite or precipitation as Zn(OH)₂ and ZnCO₃, leading to reduce fertilizer effectiveness [10, 11]. In addition, it has strong ability to bind with clay minerals, forming insoluble hydroxides that limit plant uptake [12]. In this regard, there are several options have been used to address this issue (breeding’s, foliar and soil application as well as see priming with Zinc). However, the Agronomic biofortification of staple foods has attained much attention due to cost effectiveness and sustainable option to ensure the food security against Zn malnutrition [13, 13]. Another important solution is to enhance the organic matter content in soils and reduce soil pH by using organic materials such as compost, vermicompost, and crop straw. These practices can ameliorate the calcareous nature of the soils [14]. Bashir [15] confirmed that composting is an effective, economical, and environmentally safe biological strategy attaining by the recycling of agricultural residues. Ameliorating nutrients deficient soils by compost and vermicompost [16] significantly boosts their nutritional content, organic matter levels and as well as by enhancing their chemical and biological composition [17]. Using rice husk as an organic fertilizer is an optimal strategy, as it not only improves soil productivity but also enhances water use efficiency in the field [18].

The availability of Zn in alkaline calcareous nature soils significantly influences plant Zn concentration and yield, yet wheat-growing regions, especially in Pakistan often faces chemical and physical barriers that limit Zn absorption, which has great role in grain quality and production. While, synthetic Zn fertilizers are extensively using in alkaline soils for enhancing Zn bioavailability and plant uptake. However, its combined application with compost and rice husk for Zn solubility and wheat growth in alkaline conditions are remains underexplored. Therefore, the objectives of this study were (1) to quantify the comparative efficacy of compost and rice husk alone and in combination with zinc on wheat growth, (2) to assess the potential of these organic soil amendments on soil nutrients as well as Zn mobility in alkaline soil.

Materials and methods

Study site

Soil was collected from a calcareous, zinc-deficient productive land of Dera Ghazi Khan (29° 57’ 40” N, 70° 29’ 19” E). The study site has a dry and semi-arid climate with little rainfall. The collected soil samples were transported to the University Research site for further processing and experimentation. Initially, the soil was ground to transform from large clods to granular form and passed through 2 mm sieve size for pot studies. For analyzing basic soil quality parameters, 300 g of the studied soil was further ground to pass through a 0.5 mm sieve. The experimental soil was in sandy clay loam texture with lowest organic carbon content (0.32%), alkaline in pH (7.80), and an electrical conductivity (EC) of 3.42 mS cm⁻¹. The available contents of phosphorus (P) and potassium (K) were 8.15 mg kg⁻¹ and 69 mg kg⁻¹, respectively. Additionally, the bioavailable Zn contents in AB-DTPA extractable solution was estimated by 0.32 mg kg^− 1, which exhibited the Zn deficiency in alkaline soils. Rice husk was sourced from a local rice mill, ground, and passed through a 0.25 mm sieve for soil application.

Treatments

To	Control
T1	Rice husk @ 20 t ha− 1
T2	Compost @ 10 t ha− 1
T3	Zinc @ 20 kg h− 1
T4	Rice husk @ 20 t ha− 1+ Zinc @ 20 kg h− 1
T5	Compost @ 10 t ha− 1+ Zinc @ 20 kg h− 1
T6	Compost @ 10 t ha− 1+ Rice husk@ 20 t ha− 1
T7	Compost @ 10 t ha− 1+ Rice husk@ 20 t ha− 1+ Zinc @ 20 kg h− 1

Compost production

Compost was prepared according to our previous study Bashir et al. [19], Briefly, 15 Kg of different agricultural waste such as sawdust, rice husk, and fruit waste was collected and prepared for compost production. All the selected materials were dried, chopped and transferred to100-liter plastic container. In addition, one Kg of garden soil and 200 g of urea was added and sprinkler some amount of water for microbial activity. The available contents of organic carbon (9 g/kg), N (6 g/kg), P (2.9 g/kg), K (3.4 g/kg) and Zn (32 mg/kg) were estimated from the prepared compost.

Pot experiment

A research trial was carried in the plastic pots from (Dec, 2023 to March, 2024) at the experimental field of the Department of Soil and Environmental Sciences, Ghazi University, Dera Ghazi Khan, Pakistan to assess the impact of compost, rice husk, and zinc application to ameliorate the Zn deficient calcareous alkaline soil. The experiment was arranged in complete randomized design and the studied materials were added in each experimental unit as mentioned in the treatments plan. However, compost and rice husk were applied in their respective pot with 40 g and 20 g dose respectively. The ‘Akbar’ wheat cultivar was selected for this study as this is a widely used cultivar in wheatbelt to mimic farmer’s conditions. Seeds were purchased from a local agricultural supplier in Dera Ghazi Khan, Punjab, Pakistan. This study included eight distinct treatments with three replicates. Each studied units contains 4 kg of clay loam soil. Irrigation was carried out manually using a hand sprayer. The basal doses of nitrogen (N), phosphorus (P), and potassium (K) were applied according to the recommended rate of 120:60:60 kg ha⁻¹ to each studied unit, in the form of urea, diammonium phosphate (DAP), and sulfate of potash (SOP) Khan [5]. Zn in the form of zinc sulfate (ZnSO_₄) was applied to attain the biofortification purpose. All agronomic and physiological attributes were determined at the harvest stage, while chlorophyll content was estimated during the vegetative stage. The recommended application doses for each treatment were incorporated at the time of sowing.

Soil analysis

Soil samples from each unit were collected after the harvesting of wheat plants for further analysis of soil chemical properties. The pH and electrical conductivity (EC) of the studied soil were assessed using the digital pH and EC meter with a 1:2.5 and 1:5 (w/v) soil-to-water ratio, respectively, as described by Nelson [20]. The soil organic matter (SOM) status was measured using the Walkley-Black method after the completion of soil amelioration, as described by Ahmad [19]. In addition, the available potion of zinc (Zn) in the studied soil was examined using the DTPA (diethylenetriaminepentaacetic acid) extraction method, where 20 ml of DTPA solution was used for the shaking of 2.0 g studied soil, following the procedure proposed by SSSC [21]. Available phosphorus (P) was calculated using a calorimetric method, and potassium (K) content was assessed according to the methods proposed by the Lu [22] and Sher [3].

Plant analysis

During the reproductive growth of wheat plants, the chlorophyll levels in wheat leaves were estimated from each experimental pot using the chlorophyll measuring SPAD meter (SPAD-502Plus) meter as proposed by Bashir [23]. Additionally, wheat shoots and roots were segregated and the fresh biomass was recorded. For the estimation of dry biomass, wheat shoots and roots samples were air dried for 48-hour at 70 °C in an oven. Afterward, the dried wheat shoots and grains were finely ground and digested using a combined mixture of HNO₃ and HClO₄with (9:4 v/v) ratio to calculate the Zn contents, as detailed in our previous study Nauš [24]. The agronomic parameters like Plant height, shoot and root length, leaf length, spike length, number of spikelet’s/spikes, number of leaves and number of grains/spikes were also estimated Sher [3].

Statistical analysis

All observed data from the experiment were expressed as mean values. A one-way analysis of variance (ANOVA) was performed to assess the effects of different treatments. The statistical analysis was conducted using Statistix 8.1 and R (v4.3.2)software. When significant differences were detected (p < 0.05), a post-hoc Least Significant Difference (LSD) test was applied at a 5% probability level to compare the means of different treatments Steel [25].

Results

Role of soil conditioners on soil pH and EC

Soil pH significantly varied at (p < 0.05) across all treatments (Figure. 1). This study confirmed the maximum reduction in compost and rice husk treated soil by 0.64 and 0.58 units over non-treated soil. However, the other treatments also exhibited the slight reduction in soil pH when soil was treated alone Zn or its combination with CP and RH against the non-treated soil. In the similar manner, soil EC was also influenced after soil incorporation with organic soil amendments. EC reduced by 1 and 1.2 units when combined compost and rice husk were applied along with and without Zn respectively compared to control (Fig. 1).

Fig. 1

Effect of soil amendments along with Zinc application on soil properties. All values were the average of three replicates, and the error bars are the SD of the means (n = 3) and different letters indicated that values are significantly different at p < 0.05. The treatments were referred as: To (control); T1(Rice husk @ 20 t ha^-1); T2 (Compost @ 10 t ha^-1); T3 (Zinc @ 20 kg h^-1); T4 (Rice husk @ 20 t ha^-1+ Zinc @ 20 kg h^-1); T5 (Compost @ 10 t ha^-1+ Zinc @ 20 kg h^-1); T6 (Compost @ 10 t ha^-1+ Rice husk@ 20 t ha^-1); T7 (Compost @ 10 t ha^-1+ Rice husk@ 20 t ha^-1+ Zinc @ 20 kg h^-1)

Role of soil conditioners on soil nutrients and organic matter

Results revealed that soil conditioners showed the significant increase at p < 0.05 in soil organic matter and essential nutrients such as NPK. The maximum amount observed when Zn was applied in combination with CP and RH relative to non-treated soil. SOM increased by 54% when Zn was applied in combination with CP and RHcompared to non-treated soil (Fig. 1).

Likewise, soil conditioners increased N, P and K (Fig. 2), the profound increase in soil total nitrogen was determined by 59% and 57% when CP and RH were added with and without Zn respectively over control soil. Likewise, the addition of CP and RH also expressed the prominent improvement by 50% and 42% when CP and RH with Zn were added in the Zn deficient soil. In addition, soil available-P was also accelerated after the addition of soil conditioners with and without Zn. The maximum development was observed by 40.7% and 36.2% after the addition of RH and CP along with Zn respectively over control and other remaining treatments. Moreover, the profound acceleration in soil available-K (Fig. 2) was also observed by 27.36% and 25.8% when RH and CP were added together with and without Zn respectively over control.

Fig. 2

Effect of soil amendments along with Zinc application on nutrients and Zn mobility and uptake by wheat. All values were the average of three replicates, and the error bars are the SD of the means (n = 3) and different letters indicated that values are significantly different at p < 0.05. The treatments were referred as: To (control); T1(Rice husk @ 20 t ha^-1); T2 (Compost @ 10 t ha^-1); T3 (Zinc @ 20 kg h^-1); T4 (Rice husk @ 20 t ha^-1+ Zinc @ 20 kg h^-1); T5 (Compost @ 10 t ha^-1+ Zinc @ 20 kg h^-1); T6 (Compost @ 10 t ha^-1+ Rice husk@ 20 t ha^-1); T7 (Compost @ 10 t ha^-1+ Rice husk@ 20 t ha^-1+ Zinc @ 20 kg h^-1)

Role of soil conditioners on bioavailable zinc contents

Soil conditioners showed the significant improvement at p < 0.05 in Zn mobility and accumulation. The addition of soil conditioners combination of RH and CP were applied with and without Zn prominently increased Zn in soil by 78.8% and 69% respectively over control soil. In addition, CP with and without Zn showed the effective increment in soil Zn by 73% and 53% respectively. Similarly, RH application with and without Zn exhibited the profound increment by 68% and 52% respectively over control (Fig. 2).

Soil conditioners improve Zn fortification and wheat growth

The current investigation expressed the profound increase in Zn levels were noticed in the wheat shoots as well as in wheat grains when CP, RH, Zn alone or in combination were applied in Zn deficient soil. The greater increment was recorded in Zn uptake of shoot by 79.8% and 69% when the combination of CP and RH were applied with and without Zn respectively over control. Likewise, Zn contents in shoot were boosted by 64.5% when Zn was applied without any combination. While, Zn combination with RH and CP expressed the dramatic increase by 70% and 71.1% respectively over control.

The presented results showed that addition of soil conditioners CP and RH along with Zinc in Zn-deficient soil effectively ameliorate the Zn deficiency in the alkaline soil and prominently accelerate the Zn absorption by wheat tissues as well as enhanced its accumulation in wheat grains. The greater increment was recorded by 68% when the combination of CP and RH was used along with Zn over control soil. Likewise, the profound improvement was also noticed in the combination of RH and CP without Zn by 64% in alkaline soil. While, when Zn was applied alone in Zn deficient soil expressed the prominent enhancement by 60% over non treated soil.

After the wheat harvesting, plant shoot samples from each studied unit were analyzed for the NPK absorption to examine the impact of soil conditioners. The remarkable improvement in NPK was recorded when CP, RH and Zn alone or in combinations were applied in Zn deficient soil. The profound increment in nitrogen accumulation in wheat tissues by 39.3% and 28% when the combined treatment of RH and CP was applied with and without Zn respectively over control. Likewise, the potassium accumulation was also enhanced by 53.6% and 48.5% after the addition of CP/RH with and without Zn respectively over control (Fig. 2).

The results exhibited that the application of soil conditioners separately or in combination with and without Zn prominently enhanced chlorophyll contents in wheat leaves (Fig. 4). The profound increment was determined by 32.5% and 28.5% when CP/RH combination with and without Zn was added in alkaline Zn deficient soil respectively over control. Furthermore, the remarkable improvement in plant height was also assessed by 18.9% and 14.6% when CP/RH combination was applied with and without Zn respectively against control. Moreover, all the physiological attributes of wheat have also been promoted with the addition of all these studied soil conditioners in alkaline Zn deficient soil over control soil (Figs. 3 and 4).

Fig. 3

Effect of soil amendments along with Zinc application on wheat physiological attributes. All values were the average of three replicates, and the error bars are the SD of the means (n = 3) and different letters indicated that values are significantly different at p < 0.05. The treatments were referred as: To (control); T1(Rice husk @ 20 t ha^-1); T2 (Compost @ 10 t ha^-1); T3 (Zinc @ 20 kg h^-1); T4 (Rice husk @ 20 t ha^-1+ Zinc @ 20 kg h^-1); T5 (Compost @ 10 t ha^-1+ Zinc @ 20 kg h^-1); T6 (Compost @ 10 t ha^-1+ Rice husk@ 20 t ha^-1); T7 (Compost @ 10 t ha^-1+ Rice husk@ 20 t ha^-1+ Zinc @ 20 kg h^-1)

Fig. 4

Effect of soil amendments along with Zinc application on wheat physiological attributes. All values were the average of three replicates, and the error bars are the SD of the means (n = 3) and different letters indicated that values are significantly different at p < 0.05. The treatments were referred as: To (control); T1(Rice husk @ 20 t ha^-1); T2 (Compost @ 10 t ha^-1); T3 (Zinc @ 20 kg h^-1); T4 (Rice husk @ 20 t ha^-1+ Zinc @ 20 kg h^-1); T5 (Compost @ 10 t ha^-1+ Zinc @ 20 kg h^-1); T6 (Compost @ 10 t ha^-1+ Rice husk@ 20 t ha^-1); T7 (Compost @ 10 t ha^-1+ Rice husk@ 20 t ha^-1+ Zinc @ 20 kg h^-1)

Pearson correlation and PCA analysis

The Pearson correlation of different wheat growth and yield parameters of wheat is presented in (Fig. 6). The significant and negative correlation was observed between soil pH and soil available Zn. In addition, a positive correlation was observed between DTPA-extractable Zn and Zn in shoot and grain. A strong and positive correlation was noticed between plant height with shoot length, shoot and root weight, number of spikelet’s, spike length, number of grains and 1000-grain weight ranges from (r = 0.87 to r-0.98). On the other hand, the strong and positive relation was observed in soil available nutrients and nutrients accumulation in plant tissues. In this study, PCA analysis was performed to understand the treatments effect on wheat growth parameters (Fig. 5). The PCA results revealed that the biplot of Dim1 (98.7%) and Dim2 (0.8%) that rescales the score plot and the loadings plot. The smaller the angle between each pair of arrows, the stronger the correlation between variables, these results were aligned with [26]. This suggests that addition of soil amendments is more efficient to increase overall plant growth as well as increase the Zn mobility in soil and uptake by wheat shoot as well as its accumulation in wheat grains.

Fig. 5

PCA represents the variations among soil and plants parameters after soil amendments

Fig. 6

Correlation analysis showed the variation among all the studied parameters

Discussion

Zinc (Zn) deficiency in cereal crops, especially in wheat are becoming the main food security risk in developing countries. The bio-fortification strategy, using agronomic biofortification can be a viable option to fight against the Zn deficiency in humans. In this regard, this study evaluated the impact of soil conditioners compost (CP) and rice husk (RH) along with and without Zn application in Zn deficient soil under glasshouse settings. The findings provide the valuable insights into Zn fortification strategy and highlight the importance of these soil conditioners for validating nutrient management practices developed in controlled environments. The application of Zn can accelerate the crop yield and its components through multiple mechanisms. It has potential to increase chlorophyll contents and stimulates photosynthetic activity for enhanced crop growth and development. In this regard, its application can efficiently boost the overall yield and its components [27]. The movement of Zn in soil and its accumulation in plant tissues is mainly dependent on SOM and pH. The highest pH and lowest SOM contents in Pakistani wheatbelt soils are the major contributors in micronutrients deficiency, ultimately leads to the malnutrition [28] (Fig. 7).

Fig. 7

Heat map represents the different color with positive and negative interaction of soil and plant parameters and their interaction among each other. The treatments were referred as: To (control); T1(Rice husk @ 20 t ha^-1); T2 (Compost @ 10 t ha^-1); T3 (Zinc @ 20 kg h^-1); T4 (Rice husk @ 20 t ha^-1+ Zinc @ 20 kg h^-1); T5 (Compost @ 10 t ha^-1+ Zinc @ 20 kg h^-1); T6 (Compost @ 10 t ha^-1+ Rice husk@ 20 t ha^-1); T7 (Compost @ 10 t ha^-1+ Rice husk@ 20 t ha^-1+ Zinc @ 20 kg h^-1)

This study support that among all the micronutrients, Zn is documented the most deficient micronutrient in Pakistani soils due to high pH and calcareous natures of the soils [29]. In this regard, addition of compost and rice husk along with Zn can improve soil fertility as evident by higher amount of SOM detected when treated with Zn supplementation. with the combination of CP and RH in alkaline calcareous soil which might be due the release of organic carbon contents from CP and RH during incubation. It can be demonstrated that the significant increase in SOM could led to increase soil CEC which has significant contribution to increase and retain nutrients in the alkaline soils [30, 31]. These findings are in line with the previous research performed by [32]. The previous study suggested by Ramos [32] confirmed that the addition of organic amendments can alter soil CEC and improved the soil nutrients status, thereby increasing their absorption in plant tissues. The addition of CP and RH significantly increased the microbial activity which accelerate the decomposition of organic matter, results the release of organic acids, which help can regulate soil pH. In alkaline soils, the organic acids can contribute to facilitate the mobility of fixed nutrients especially NPK and Zn. The findings of this study support that the addition of CP and RH showed the higher improvement in soil available NPK and Zn compared to the control. Similar results were expressed by Dawar [33] confirmed that the addition of CP along with Zn showed the prominent increase in soil available-P by 48%, total nitrogen by 84.57%, OM by 1.23% at 10% CP along with 2.5% Zn dose.

In present study, the application of Zn at the rate of 20 kg ha^− 1 with compost and Rice husk significantly enhanced the bioavailability of Zn and increased accumulation in the wheat grain. Moreover, the breakdown and mineralization of CP and RH in alkaline soil could facilitate the discharge of organic acids, which could contribute to reduce the soil pH [26], thereby increasing the mobility of Zn in alkaline soils [13]. These results were supported by Yassen [27] indicated that the amelioration of alkaline soil using organic soil conditioners prominently reduced the soil pH because of excessive discharge of organic acids during incubation, which could facilitate the mobilization of fixed nutrients especially phosphorus, zinc and nitrogen [34]. The addition of Zn along with organic soil conditioners efficiently enhance the productivity of the soil by reducing soil pH and thereby promoted the soil nutrients status. It has been established that the application of Zn to soil in the form of ZnSO₄·7 H₂O have strong impact to enhances Zn mobility in soil as well as its uptake by wheat grain [35]. Similarly, Akram [27] described an increase in grain yield, particularly in wheat plants, following zinc application.

In current study, the addition of CP and RH along with Zn expressed the significant contribution in wheat growth, nutrients absorption in wheat tissues as well in wheat grain. It can be attributed that organic byproducts can accelerate the activity of soil microbial communities in the soils with the provision of nutrients and substrate to them, which can regulate nutrient cycling as well as enhance the production of growth hormones like auxins, ultimately improve root and shoot development. In addition, better Zn absorption played a central role in boosting wheat growth and yield. Zn is essential for various physiological processes, including enzyme synthesis, chlorophyll biosynthesis, and carbohydrate metabolism [36]. Improved chlorophyll production and photosynthesis directly correlate with higher yields. The findings align with previous research, showing that combining higher Zn concentrations (0Zn to 10.0Zn) with 10 C treatment significantly enhanced wheat yield attributes [33]. This improvement is primarily attributed to the betterment of soil chemical properties and the increased availability of nutrients. Similar results were reported by Liu [37], they found that the incorporation of organic materials along with chemical fertilizers could enhance nutrients availability in alkaline soils. This can potentially enhance crop growth at early stages of development. These results are supported by the findings of Yadav [38], they found that addition of Zn fertilizers effectively promote fortification of Zn in Zn-deficient soils. The application of Zn also enhances the accessibility of Zn, crop growth, grain yield and the concentration of Zinc in the wheat grains [35]. The application of Zn at the rate of 20 kg ha^− 1 with compost and rice husk also increased the chlorophyll content in wheat leaves which play ley role in photosynthesis process and food production [38].

Overall, the finding of this study suggests that, Zn application sustained grain yield of wheat, Similar results were observed by Liu [37] confirmed that Zn application to alkaline soils could accelerate the Zn absorption in leaves that ultimately improved the wheat nutritional quality and grain yield, particularly in Zn-deficient soils. The significant increase in yield and yield attributes were directly correlated with profound improvement in soil fertility [39]. The improvement in Zn uptake and accumulation in plants tissues could accelerate the crop development and facilitate to increase crop yield [40]. Similarly, Ahmed [41] found that the application of organic materials can promote crop development. Zinc fertilization is designed to boost plant Zn absorption Faran [36], while organic materials are also recognized for their role in supporting crop growth [42].

Conclusion

Zn deficiency in alkaline soils causes severe yield penalties in wheatbelt of Pakistan. This study quantified the incorporation of organic soil conditioners, such as compost (CP) and rice husk (RH), with and without Zn supplementation to alkaline soils for wheat crop. Results indicate that incorporation of Zn prominently promoted the physiological attributes of wheat, as well as accelerate the Zn accumulation in wheat shoots and grains. In addition, presented results established the Zn fortification using CP and RH through agronomic methods is the most suitable strategy to addressing Zn deficiency in soils. Furthermore, the Zn bioavailable concentration was prominently increased by 78.8% and 69% when RH and CP were applied with Zn in alkaline soil. This study provides the future directions to determine the effectual methods of Zn application for increasing the absorption and accumulation of Zn in wheat grains to address the human’s demand. This study implicates that wheat yield can be improved with Zn application to alkaline soil conditions. Majority of soils in Pakistan wheatbelt suffer with Zn deficiency, if farmers apply a minimum amount of Zn to highly alkaline soils, then yield penalties can be minimized.