RESPONSE OF MAIZE TO A NOVEL ORGANIC POTASSIUM FERTILIZER DEVELOPED FROM FRUIT AND VEGETABLE WASTES

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1 ISSN Pak. J. Agri., Agril. Engg., Vet. Sci., 2013, 29 (1): 1-12 RESPONSE OF MAIZE TO A NOVEL ORGANIC POTASSIUM FERTILIZER DEVELOPED FROM FRUIT AND VEGETABLE WASTES 1 S. Kubar 1, Zia-ul-hassan 1, A. N. Shah 1, I. Rajpar 1 and S. A. Qureshi 2 1 Department of Soil Science, Sindh Agriculture University, Tandojam, Pakistan 2 Agriculture Research Sindh, Tandojam, Pakistan ABSTRACT High cost of synthetic K fertilizers and their unavailability are the serious risks to sustainable maize production in Pakistan. Hence, to explore the alternate sources of K for maize production, a pot study was conducted to evaluate the efficacy of a novel organic K fertilizer, developed from fruit and vegetable wastes. Six combinations i.e (control), 30-00, 00-30, 30-30, 60-00, kg ha -1 K chemical and oraganic K fertilizers were applied in completely randomized design (CRD) with three repeats using maize (cv. Akbar) as a test crop. The synthetic K was applied as sulphate of potash and for organic K two different batches of organic fertilizers were prepared and applied at the rate of 300 kg ha -1. The crop received recommended doses of nitrogen (150 kg ha -1 ) as urea and phosphorus (75 kg ha -1 ) as diammonium phosphate. The soil under study was heavy in texture, alkaline in nature, free from salinity hazards; low in organic matter and deficient in AB-DTPA extractable. Potassium K nutrition improved various growth traits, K accumulation and biomass production of maize. Higher K application rate (60 kg ha -1 ) was significantly superior than lower K application rate (30 kg ha -1 ). Generally, inorganic K was significantly better than the organic K in improving various traits of maize at both K application rates, except for the shoot diameter, which responded more to organic K (30 kg ha -1 ). The integrated use of K was more effective than all other K treatments in elevating different growth parameters of maize, except length and shoot diameter of maize that were highest at the inorganic K application rate of 60 kg ha -1. Hence, the integrated use of K saved 50% of the chemical K fertilizer. Overall, K nutrition enhanced various traits of maize, viz. shoot length (9 to 38%), shoot diameter (35 to 95%), shoot fresh biomass (29 to 79%), shoot dry biomass (44 to 219%), number of leaves plant ha -1 (7 to 60%), leaf area (14 to 40%) and K concentration (2-fold to 4.6-fold). The study concluded that K application at 60 kg ha -1, by integrating 30 kg ha -1 chemical fertilizer with 30 kg ha -1 organic fertilizer, improved the growth and biomass production of maize. Further validation of these results is warranted under field condition. Keywords: Biomass production, growth, maize, organic K fertilizer, potassium. Corresponding author: zhnshah@gmail.com 1

2 INTRODUCTION Maize (Zea mays L.) is an important cereal crop of world. In Pakistan, maize crop occupies an area of ha with a total production of tons and an average yield of 3415 kg ha -1. The average yield of maize in Pakistan is far below than that obtained by her neighbor China (5556 kg ha -1 ) or when compared to the global average yield of maize (5109 kg ha -1 ) (GoP, 2010). According to the plant nutritionists, the rapid mining of potassium (K) from Pakistani soils could be the main culprit for such crop yield stagnant situations that may even result into reduction of crop yield (Zia-ul-hassan et al., 2011). Potassium (K) is considered as the most important essential major plant nutrient due to its cascade of roles in plant physiology and biochemistry (Nawaz et al., 2006; Zia-ul-hassan et al., 2011). Apart from its important roles in plant physiology and biochemistry, K has also been considered as the major yield and quality contributing nutrient in maize production (Bukhsh et al., 2012). The involvement of K in maize nutrition ensures optimum yield and quality (White, 2003; Bukhsh et al., 2012). In an elegant study, Nawaz et al. (2006) reported high K requirement of 15 maize genotypes of Pakistan. These researchers noted severe reduction in shoot and root biomass of all the maize genotypes under K deficiency stress. On the other hand, adequate K nutrition increased biomass accumulation of all the maize genotypes under study. The K-use-efficient genotypes had higher root biomass under K deficient condition which suggested that these genotypes were able to explore K from larger volumes. The positive effects of K on maize growth, yield and quality parameters are now well established in the literature (Chaudhry and Ahmad, 2000; Bukhsh et al., 2012). The growth and yield components of maize like leaf area (Rasheed, 2002; Meille and Pellerin, 2008), crop growth rate, plant height, number of grain cob -1, cob length, 1000-grain weight, grain and biological yield are significantly increased by K application (Pettigrew, 2008; Bukhsh et al., 2012). In line to these positive effects of K nutrition on maize growth and yield parameters, the quality traits of maize grains such as crude protein content (Usherwood, 1985), crude starch content (Mahmood et al., 2000) and crude oil content (Ali et al., 2004) also improved by adequate amounts of K application to maize crop. The maximum (almost 2/3) K absorption and accumulation occurred at flowering stage in maize (Shang-wen et al., 2009). The K uptake of maize is very rapid and it can go beyond 05 kg K ha -1 daily during first 07 weeks of sowing (White, 2003), while the above ground parts of a mature maize crop can accumulate 300 kg K ha -1 (Karlen, 1988). The assimilation and accumulation of K by K-efficient maize genotypes are always higher than their inefficient counterparts (Shang-wen et al., 2009). Hence, it is understood that in the absence of adequate K nutrition optimum yield and quality of a maize crop can t be achieved. However, in view of the scorching prices of K fertilizers in Pakistan, the plant nutritionists must search alternate sources of K nutrition of crops. Pakistan has been facing the problem of ever increasing amounts of solid waste. These organic wastes successfully supplement plant nutrition, improve soil health and environmental quality and reduce input cost of chemical fertilizers, if they are effectively composted (Arshad et al., 2007; Ahmad et al., 2008a). These composted organic wastes are enriched with nutrients, like nitrogen (N), phosphorus (P) and potassium (K) and/ 2

3 or blended with plant growth regulators, such as auxin precursor L-tryptophan, to make various types of organic fertilizer products (Arshad et al., 2007).The soil application of such organic fertilizers at substantially lower rates ( 300 kg ha -1 ), supplemented with only a quarter to half of the recommended dose of chemical fertilizers, enhances crop yields, quality, nutrient uptake and soil health (Arshad et al., 2004; Ahmad et al., 2006a,b; Asghar et al., 2006; Tahir et al., 2006; Arshad et al., 2007; Ahmad et al., 2008a,b). Despite these encouraging results, the technology of developing low-cost, nutrient enriched, organic fertilizers is only limited to the formulation of nitrogen enriched organic fertilizers which were also successfully used to benefit the nutrition of various crops. However, no any study is reported in relation to the development of organic K fertilizer to support inorganic K nutrition of crops in quest of sustainable crop production and environmental promotion.this study aims at evaluating the response of maize to a novel organic potassium fertilizer developed from fruit and vegetable wastes. MATERIALS AND METHODS A pot experiment was conducted in the wire-house of the Department of Soil Science, Sindh Agriculture University, Tandojam, Pakistan. Six different combinations i.e (control), 30-00, 00-30, 30-30, 60-00, kg K ha -1 of chemical and oraganic K fertilizers were arranged in completely randomized design (CRD) with three repeats. Maize (cv. Akbar) was used as a test crop. The soil and required doses of inorganic and organic fertilizers were thoroughly mixed and filled in pots of 7 kg capacity. The inorganic K was supplied as sulphate of potash (50% K 2 O) and organic K was applied by preparing two different batches of organic K fertilizers from fruit and vegetable wastes, containing 30 and 60% K 2 O as described by Arshad et al. (2007). These organic fertilizers were 300 kg ha -1. The crop received recommended doses of nitrogen (150 kg ha -1 ) and phosphorus (75 kg ha -1 ) as urea (46% N) and diammonium phosphate (18% N and 46% P 2 O 5 ). The soil used in the experiment was collected through standard procedures (Ryan et al., 2001) from Latif Experimental Farm, Sindh Agriculture University, Tandojam. It was then properly processed and analyzed for texture, electrical conductivity, ph, organic matter and AB-DTPA extractable K, following standard methods (Ryan et al., 2001). The chemical analyses revealed that the soil under study was heavy in texture (40% clay), alkaline in nature (ph: 8.1), free from salinity hazards (EC: 1.40 ds m -1 ). Moreover, the soil was poorly fertile and found low in organic matter (0.64%) and AB-DTPA extractable potassium (105 mg kg -1 ). The sowing was done by marking 2 cm deep hole with pencil in each pot. Afterwards, only five seedlings of uniform size were allowed to grow for six weeks in each pot and then harvested.the crop was irrigated according to its requirement. The crop was kept free from weeds by daily monitoring and hand plucking of weeds. All the other recommended agronomic practices were followed throughout the life span of the crop. The pots were rotated twice a week to avoid any environmental influence. After six weeks, the maize plants were harvested to record their shoot length, shoot diameter, shoot fresh weight, shoot dry weight, number of leaves and leaf area. Shoot K concentration was determined as described by Zia-ul-hassan et al. (2011). The collected data were subjected to requisite statistical analyses using Statistixver 8.1. The analysis was 3

4 done by following completely randomized design. The treatment means were separated at alpha RESULTS The mean squares from analysis of variance (65.9) reflected that different K treatments significantly (p <0.001) affected all the traits of maize (Table 1). Application of K increased all the growth parameters of maize, viz. length, diameter and biomass production, enhanced the efficacy of the photosynthetic apparatus (number and area of leaves) and K accumulation in plant. Higher K application rate (60 kg ha -1 ) was significantly superior to the lower application rate (30 kg ha -1 ), irrespective of their sources. Furthermore, inorganic K nutrition increased all the traits of maize more significantly over the same level of organic K (Figure 1 and 2). However, shoot dry biomass was recorded significantly more under organic K nutrition at lower K application rates (Figure 1). Minimum shoot length of maize (34.1 cm) was obtained where no K was applied (control). Applying 30 kg K ha -1 increased shoot length and this increase was more in case of inorganic K nutrition (38.0 cm) as against organic K nutrition (37.0 cm). Where K was 60 kg ha -1, the maximum shoot length (47.0 cm) was obtained through inorganic K nutrition, followed by the treatment receiving integrated K nutrition (43.3 cm) and through organic K fertilizer alone (41.3 cm). Application of 30 kg K ha -1 through inorganic and organic K fertilizers increased shoot length up to 12% and 9%, respectively, over control. Similarly, as compared to control, application of 60 kg K ha -1 through inorganic and organic K nutrition increased shoot length up to 38% and 21%, respectively. Moreover, K 60 kg ha -1, by integrating both K sources, increased shoot length of maize up to 27% (Figure 1). Similarly, minimum shoot diameter of maize (5.6 mm) was obtained where no K was applied (control). Application of 30 kg K ha -1 increased shoot diameter and this increase was more in case of organic K nutrition (7.8 mm) as against inorganic K nutrition (7.6 mm). Where K was 60 kg ha -1, the maximum shoot diameter (10.1 mm) was obtained through inorganic K nutrition, followed by the treatment receiving integrated K nutrition (10.6 mm) and through organic K fertilizer alone (10.5 mm). Application of 30 kg K ha -1 through inorganic and organic K fertilizers increased shoot diameter up to 35% and 39%, respectively, over control. Similarly, as compared to control, application of 60 kg K ha -1 through inorganic and organic sources increased shoot diameter up to 95% and 87%, respectively. Moreover, shoot diameter of maize increased up to 89% by the integrated application of 60 kg K ha -1 (Figure 1). Likewise, minimum shoot fresh biomass (5.11 g) was recorded in control. Applying 30 kg K ha -1 increased shoot fresh biomass and this increase was more in case of inorganic K source (6.77 g) as against organic K source (6.6 g). The maximum shoot fresh biomass (9.17 g) was 60 kg K ha -1 applied through the integration of organic and inorganic sources, followed by the treatment receiving inorganic K nutrition (8.33 g) and through the single application of organic K fertilizer (7.97 g). Application of 30 kg K ha -1 through each inorganic and organic K fertilizers increased shoot fresh biomass up to 32% and 29%, respectively, over control. Similarly, as compared to control, application of 60 kg K ha -1 by each inorganic and organic K nutrition increased shoot fresh biomass up to 63% and 56%, 4

5 respectively. Moreover, shoot fresh biomass increased up to 79% by the integrated application of 60 kg K ha -1 (Figure 1). Furthermore, minimum shoot dry biomass of maize (1.95 g) was obtained where no K was applied (control). Table 1. Significance of mean squares from analysis of variance of various parameters of maize in relation to integrated use of potassium. (*, ** and *** represent significance levels at alpha 0.05, 0.01, and obtained through honestly significant difference (HSD) test. NS represents non-significance). Parameter Mean square for K treatments Shoot length 65.90*** Shoot diameter 13.97*** Shoot fresh biomass 6.33*** Shoot dry biomass 9.35*** Number of leaves 4.26*** Leaf area *** K concentration 4.83*** Applying 30 kg K ha -1 enhanced shoot dry biomass and this increase was more in case of inorganic K nutrition (3.55 g) against organic K nutrition (2.81 g). Where K was 60 kg ha -1. The maximum shoot dry biomass (6.22 g) was obtained through the integration of K 60 kg ha -1, followed by the same rate of inorganic K (5.98 g) and then organic K fertilizer alone (5.17 g). Application of 30 kg K ha -1 through inorganic and organic K fertilizers increased shoot dry biomass up to 82% and 44%, respectively, over control (no K application). Similarly, as compared to control, application of 60 kg K ha -1 through inorganic and organic K nutrition increased shoot dry biomass up to 207% and 165%, respectively. Moreover, shoot dry biomass of maize increased up to 219% by the integrated application of 60 kg K ha -1 (Figure 1). On the same pattern, minimum number of leaves of maize (5.04) was obtained where no K was applied (control). Applying 30 kg K ha -1 increased number of leaves and this increase was more in case of inorganic K nutrition (5.82) as against organic K nutrition (5.38). Where K was 60 kg ha -1, the maximum number of leaves (8.05) was obtained through integrated K nutrition, followed by the treatment receiving inorganic K nutrition (7.27) and through organic K fertilizer alone (7.04). Application of 30 kg K ha -1 through inorganic and organic K fertilizers increased number of leaves up to 15% and 7%, respectively, over control (no K application). Similarly, as compared to control, application of 60 kg K ha -1 through inorganic and organic K nutrition increased number of leaves up to 44% and 40%, respectively. Moreover, number of leaves of maize increased up to 60% by the integrated application of 60 kg K ha -1 (Figure 2). Similarly, minimum leaf area of maize (46.7 cm 2 ) was obtained where no K was applied (control). Applying 30 kg K ha -1 increased leaf area and this increase was more in case of inorganic K nutrition (55.0 cm 2 ) as against organic K nutrition (53.0 cm 2 ). 5

6 Figure 1. Shoot length, diameter and biomass of maize in relation to potassium application through inorganic and organic fertilizers at varying levels (Tukey s honestly significant difference at alpha 0.05 for shoot length 3.254, shoot diameter 2.204, shoot fresh weight and shoot dry weight 1.082). Where K was 60 kg ha -1, the maximum leaf area (65.3 cm 2 ) was obtained through integrated K nutrition, followed by the treatment receiving inorganic K nutrition (61.0cm 2 ) and through organic K fertilizer alone (58.4cm 2 ). Application of 30 kg K ha -1 through inorganic and organic K fertilizers increased leaf area up to 18% and 14%, respectively, over control (no K application). Similarly, as compared to control, application of 60 kg K ha -1 through inorganic and organic K nutrition increased leaf area up to 31% and 25%, respectively. Moreover, leaf area of maize increased up to 40% by the integrated application of 60 kg K ha -1 (Figure 2). Moreover, minimum K concentration of maize (0.77%) was obtained where no K was applied (control). Applying 30 kg K ha -1 increased 6

7 K concentration and this increase was more in case of inorganic K nutrition (2.43%) as against organic K nutrition (2.3%). Where K was 60 kg ha -1, the maximum K concentration (4.28%) was obtained through integrated K nutrition, followed by the treatment receiving inorganic K nutrition (3.82%) and through organic K fertilizer alone (3.4%). Application of 30 kg K ha -1 through inorganic and organic K fertilizers increased K concentration up to 2.2-fold and 2.0-fold, respectively, over control (no K application). Similarly, as compared to control, application of 60 kg K ha -1 through inorganic and organic K nutrition increased K concentration up to 4.0-fold and 3.4-fold, respectively. Moreover, K concentration of maize increased up to 4.6-fold by the integrated application of 60 kg K ha -1 (Figure 2). Figure 2. Number of leaves, leaf area and K concentration of maize in relation to potassium application through inorganic and organic fertilizers at varying levels (Tukey s honestly significant difference at alpha 0.05 for number of leaves 1.448, leaf area and K concentration 0.233). 7

8 DISCUSSION The present study endorsed the beneficial effects of potassium (K) in maize nutrition. Inclusion of K in maize nutrition significantly improved the growth, K accumulation and biomass production of maize (Table 1, Figure 1 and 2). Higher K application rate (60 kg ha -1 ) was significantly more superior to the lower K application rate (30 kg ha -1 ). The data (Figure 1 and 2) depict that the K nutrition improved various traits of maize, viz. shoot length (up to 38%), shoot diameter (up to 95%), biomass production (up to 2.2-fold), number of leaves plant -1 (up to 60%), leaf area (up to 40%) and K concentration ( up to 4.6-fold). The results of the present study are in-line with many studies conducted in recent past highlighting the positive effects of K on maize growth, yield and quality parameters (Chaudhry and Ahmad, 2000; Nawaz et al., 2006; Bukhsh et al., 2012). Some other studies also reported that K nutrition improves the growth and yield components of maize like leaf area (Rasheed, 2002; Meille and Pellerin, 2008), crop growth rate, plant height, number of grains cob -1, cob length, grain weight, grain and biological yield (Pettigrew, 2008; Bukhsh et al., 2012). Similarly, the quality traits of maize grains such as crude protein content (Usherwood, 1985), crude starch content (Mahmood et al., 2000) and crude oil content (Ali et al., 2004) were also improved by adequate K application. In this study, the integrated use of inorganic and organic K fertilizers at 60 kg ha -1 enhanced maize growth and biomass production significantly superior to other K treatments (Figure 1 to 2). Earlier too, it has been reported by various research workers that the soil application of nutrient enriched organic fertilizers at substantially lower rates ( 300 kg ha -1 ), supplemented with only a quarter to half of the recommended dose of chemical fertilizers, enhances crop yields, quality, nutrient uptake and soil health (Arshad et al., 2004; Ahmad et al., 2006a,b; Asghar et al., 2006; Tahir et al., 2006; Arshad et al., 2007; Ahmad et al., 2008a,b; Abedi et al., 2010). Earlier, it has been advocated that the organic wastes present in huge amounts can be turned into valuable compost products for organic crop production. In this way, by using these organic wastes as organic fertilizers, the deteriorating environmental quality can be improved. Raw use of such organic wastes is difficult because of difficulties in their transportation and handling, their wider C:N ratio, high application rates, nutrient overloading, weed seeds, pathogens, and metal toxicities (Ahmad et al., 2007a). Zahir et al. (2007a) found that application of N and L-TRP-enriched 500 kg ha -1 was as effective as full dose of N fertilizer in improving growth and yield of wheat, saving 30% N fertilizer. Tahir et al. (2006) found in a pot study that organic/ biofertilizer supplemented with 57 kg N ha -1 (50% of full dose of N fertilizer) was more effective in improving the growth and yield of tomato as compared to full dose of N fertilizers. It increased the root length, dry weights of root and shoot, number of fruits pot -1 and fruit weight pot -1 up to 91, 98, 62, 71 and 46%, respectively, over control, in first trial, while in second trial, an increase up to 63, 115, 70, 81 and 68%, respectively, over control, was recorded. Similarly, N concentration in dry fruit and straw of tomato plants were significantly improved (35 and 43% over control, respectively) in case of biofertilizer plus 50% N 8

9 fertilizer in both trials. Ahmad et al. (2008a) observed that the nitrogen enriched compost blended with or without IAA/GA3 supplemented with half dose of N fertilizer was as effective as full dose of N fertilizer in improving growth and yield of maize and saved 25% N fertilizer. However, kinetin added compost was better than IAA/GA3-added compost when compared with recommended dose of N fertilizer. It significantly improved yield (6.2 kg ha -1 ) and N uptake (6.7%) of maize and wheat by 5.9 and 6.1%, respectively over full dose of N fertilizer. Ahmad et al. (2007b) elucidated that the application of nitrogen and L-tryptophan enriched compost significantly promoted growth and yield of both wheat and maize crops. Application of enriched compost with 50% N was the most effective in improving grain yield and yield contributing parameters compared to control. Similarly, N, P and K contents of the wheat and maize plants were significantly improved upon application of enriched compost plus N fertilizer. Similarly, Asghar et al. (2006) concluded that nitrogen enriched compost, blended with L-tryptophan, improves the growth and yield of radish. Enriched compost + 50% recommended nitrogen fertilizer produced significantly better results in almost all the parameters except number of leaves plant -1 and root length. Other parameters like leaf area, root girth, total biomass plant -1, and yield ha -1 increased by 82, 68, and 167.6%, respectively as compared to control. Zahir et al. (2007b) also reported that IAAblended N-compost with 50% of N fertilizer was comparable with full dose of N fertilizer for improving growth and yield of wheat, saving 25% N fertilizer. However, application of kinetin blended N-enriched compost increased the grain yield (9.1%) and uptake of nutrients i.e. NPK uptake (5.6, 8.6 and 7%, respectively) over full dose of N fertilizer. Ahmad et al. (2006a) compared the effectiveness of raw enriched organic waste with enriched composted prepared from fruit and vegetable wastes in pot and field experiments and reported that enriched compost with 44 N (25% of full dose of N) was superior over the raw organic waste supplemented with N fertilizer and caused significant improvement in growth, yield and nutrient uptakes of maize. This discussion not only demonstrates the benefits of using novel organic fertilizers developed from fruits and vegetables waste material but also encourages plant nutritionists to explore further the domain of developing organic fertilizers by utilizing fruits and vegetables organic waste material for low-input sustainable crop production. CONCLUSION The study concluded that K application at 60 kg ha -1, by integrating 30 kg K ha -1 from each chemical fertilizer and K enriched compost, developed from fruits and vegetables organic waste material improves the growth and biomass production of maize. ACKNOWLEDGEMENTS This study was funded by the Department of Agriculture, Government of Sindh, through Competitive Agriculture Research Grant Scheme. 9

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