Maximizing the Yield of Black Cute Rice using Human Urine and NPK Fertilizer

1. INTRODUCTION

Rice (Oryza sativa L.) is the most important food crop in the world and the main source of food for more than half of the world's population. Rice accounts for 35-75% of the calories consumed by more than three billion Asians. Rice is grown on an area of 154 million hectares each year (11%) of agricultural land worldwide [1]. Rice is one of the food crops cultivated by most of the world's population [2].

Currently, several types of rice are rich in anthocyanins, such as black rice, red rice, black glutinous rice, and others [3]. Black glutinous rice has different properties from black rice because of its higher amylopectin content. The productivity of black glutinous rice could not be separated from the application of fertilizer. Fertilizer is an organic or inorganic material that was applied to the soil to add one or more nutrients needed for plant growth. Human urine is a natural resource that can be used as natural fertilizer because it still contains nutrients. According to Nabavi-Pelesaraei [4], the growing waste production is a result of the increased human population.

In human feces, urine was mostly nitrogen (N), phosphorus (P), and potassium (K) [5]. Human urine contained large amounts of primary plant nutrients, namely, nitrogen (N), phosphorus (P), potassium (K), and secondary nutrients, including sulfur (S), calcium (Ca), and Magnesium (Mg). Urine had an element of N, P, K value of 18:2:5 [6] and for urine mixed with flush water, a ratio of N, P, K, S was 15:1:3:1 [7]. The chemical composition of human urine depends on time, diet, climate, physical activity, and body size [8]. Beaune [9] stated that however human urine is composed of nitrogen (N), inorganic potassium (K), phosphorus (P), Calcium (Ca), Sulfur (S), and Magnesium (Mg) directly absorbable by plants, similarly to commercial fertilizers [6, 10, 11].

Too much human urine application can lead to the accumulation of sodium (Na) and nitrogen (N) in the soil and ultimately inhibit plant growth [12]. However, it contained some salts [11], and drugs [13, 14]. Regarding the problem of salt (Na), too much human urine volume applied to agricultural land as fertilizer can simultaneously lead to excess sodium in the soil and ultimately in plants. Sodium inhibited plant growth because it interferes with water uptake at the roots, spreading soil particles, limiting root growth, and/or interfering with the uptake of competitive nutrients [12]. Sheneni et al. [15] added that male and female urine increased the growth rate and phytochemical constituents of Zea mays by 50, 100, and 150 ml clump^-1, respectively. High urine concentration (200 ml clump^-1) inhibited the growth of Zea mays. This study showed that human urine was a good source of fertilizer at very low concentrations.

The nutrient content in human urine was relatively low. The need for sufficient rice plant nutrient elements that industrial fertilizers were needed, namely NPK compound fertilizers. Aksani et al. [16] in their research concluded that the fertilizer dose of the best response to vegetative and generative growth of rice plants was 250 kg ha^-1 NPK fertilizer and 300 kg ha^-1 urea. According to Nafiu et al. [17] a dose of 200 kg ha^-1 NPK was sufficient for optimal growth, dry matter production, and yield in field and greenhouse conditions. Also by Samira Samira et al. [18], the application of NPK significantly affected plant height, tillers number, panicle number clump^-1, total grain number panicle^-1, percentage of unfilled grain, filled grain panicle^-1, 1,000-grain weight, and potential yield ha^-1. Makinde et al. [19] stated that the combination of organic fertilizer and NPK with a ratio of 75:25 was the best. Paiman et al. [20], added that the use of NPK fertilizer can increase the tillers number clump^-1, root dry weight, straw dry weight, and grain dry weight of rice.

Based on the literature search, there has been no comprehensive research related to the combination of liquid organic human urine and NPK compound fertilizer to maximize the productivity of black cute rice in Litosol soil. No previous research has discussed the fertilizer combination of liquid organic human urine and NPK to increase the yield of black cute rice. A combination of liquid organic human urine and NPK has contributed to increasing the productivity of black cute rice. This study aims to determine the best treatment combination of human urine and NPK fertilizer dose to maximize the yield of the black cute rice.

2. MATERIALS AND METHODS

3. RESULTS

3.2. Growth and Yield of Rice

The ANOVA on productive tillers number, straw dry weight, and grain dry weight of black cute rice is presented in Table 2.

Table 2.

Treatment	Productive tillers number (stem clump-1)	Straw dry weight (g clump-1)	Grain dry weight (t ha-1)
P	13.41**	15.66**	16.08 **
K	0.95 ns	1.03 ns	1.98 ns
P × K	3.12 *	4.52**	4.49 **
CV (%)	18.26	13.19	13.11

Remarks: P = dose of human urine fertilizer, K = dose of NPK fertilizer, P × K = interaction of P and K, CV = coefficient of variation, ns = non significance, * = at 5% significantlevel, and ** = at 1% significantlevel.

Table 2 shows that there was a significant interaction between the dose of human urine and NPK on productive tillers number (stems), straw dry weight (g clump^-1), and grain dry weight (t ha^-1).

The DMRT results on average productive tillers number, straw dry weight, and grain dry weight in various doses of human urine and NPK fertilizer can be seen in Table 3.

(Table 3) explains that the highest number of productive tillers was the interaction of human urine dose of 1000 L ha^-1and NPK dose of 150 kg ha^-1, which was not different from the interaction between human urine of 1,000 L ha^-1and NPK of 300 kg ha^-1or without NPK fertilizer. Besides that, it is also not different from the dose of human urine of 500 L ha^-1with a dose of NPK fertilizer at a dose of 0, 150, and 300 kg ha^-1 or without human urine and NPK dose of 300 kg ha^-1. While the productive tillers number had the least interaction without human urine and without NPK fertilizer, which was not different from without human urine and NPK dose of 150 or 300 kg ha^-1. Besides, it was also not different from the interaction of human urine dose of 500 L ha^-1and NPK dose of 150 or 300 kg ha^-1.

Table 3.

Human urine fertilizer (L ha-1)	NPK Fertilizer (kg ha-1)	Observations
		Productive tillers number (stem clump-1)	Straw dry weight (g clump-1)	Grain dry weight (t ha-1)
0	0	8.67 b	19.00 c	5.333 d
	150	9.07 b	20.53 bc	5.866 cd
	300	10.67 ab	21.00 bc	5.917 cd
500	0	11.33 ab	27.47 a	6.525 bcd
	150	12.07 ab	25.87 ab	7.350 abc
	300	12.33 ab	26.20 ab	7.217 abc
1,000	0	13.67 a	27.27 a	7.350 abc
	150	14.87 a	26.27 ab	8.117 ab
	300	14.53 a	31.67 a	8.633 a

Remarks: The number in the same column followed by the same characters are not significantly different based on DMRT at a 5% significant level.

The highest straw dry weight (Table 3) was achieved in the interaction of human urine dose of 1000 L ha^-1and NPK fertilizer dose of 300 kg ha^-1 but not different with human urine interactions dose of 1000 L ha^-1and NPK fertilizer doses of 0 and 150 kg ha^-1. In addition, it was not different from the interaction of human urine dose of 500 L ha^-1and NPK doses of 0, 150, or 300 kg ha^-1. The lowest was without the application of human urine and NPK fertilizer (control), but it was not different from without human urine and NPK doses of 150 or 300 kg ha^-1. At different doses of NPK fertilizers, in the same human urine dose, there was no difference in straw dry weight, both the human urine doses of 0, 500, and 1,000 L ha^-1. The role of human urine was more dominant than NPK fertilizer.

Table 3 shows that the highest grain dry weight was achieved at the interaction of the human urine dose of 1000 L ha^-1and NPK fertilizer dose of 300 kg ha^-1, but not different from human urine interactions dose of 1000 L ha^-1and NPK doses of 0 and 150 kg ha^-1. Besides that, it was also not different from the interaction of human urine dose of 1000 L ha^-1and NPK doses of 150 and 300 kg ha^-1. The lowest was without human urine and NPK fertilizer, but it was not different from without human urine and NPK dose of 150 or 300 kg ha^-1. The effect of a combination dose of human urine and NPK fertilizer on grain dry weight can be seen in Fig. (1).

Fig. 1 shows that the productive tillers number was at least in the interaction without human urine and NPK 150 kg haˉ¹ or without NPK fertilizer and the most interactions with human urine dose of 1,000 L ha^-1, andNPK doses of 0, 150, or 300 kg ha^-1. The combination of human urine dose of 1,000 L ha^-1 with various doses of NPK compound fertilizer or without NPK compound fertilizer did not show a significant difference.

4. DISCUSSION

Human urine played a greater role in the productive tillers number. The most striking advantage of liquid organic fertilizers was the absorption of nutrients runs faster than fertilizers given through the roots [22]. It was because the leaves have stomata that could open and close mechanically so that rice plants could grow well. Liquid organic fertilizer contained micronutrients. Generally, plants often lack micronutrients if they only rely on root fertilizers, which mostly contain macronutrients. Samanhudi et al. [23], stated that microelements are elements that plants need in small amounts. Although only absorbed in small amounts, it was very important to support the success of the process in plants. Micronutrient elements play a role in helping smooth the photosynthesis process and increasing the chlorophyll content. According to Yunus and Dinana [23], an increase in chlorophyll content would increase the plant photosynthesis rate resulting in photosynthate content, ultimately increasing plant growth and tillers number.

In addition, the faster-absorbed process of nutrients than through the soil, liquid organic fertilizer of human urine had a more complete nutrient composition. Beaune et al. [8] human urine was freely available around the world and composed of nitrogen (N), inorganic potassium (K), phosphorus (P), and other nutrients directly absorbable by plants. Pradhan et al. [11]; Egigu et al. [6] stated that human urine was composed of nitrogen (N) (as urea (75-90%) and ammonium), inorganic potassium (K), phosphorus (P), Calcium (Ca), Sulfur (S), and Magnesium (Mg) directly absorbable by plants, similarly to commercial fertilizers. According to Elhani et al. [24], productive tillers number depends on natural resources such as water, nutrients, and light. Grain yield up to 70% came from the number of productive tillers [25].

The high straw dry weight in the application of human urine and NPK fertilizer were caused by the role of macro and micronutrient elements contained in human urine and elements of N, P, and K were contained in NPK fertilizer. Nitrogen is a macronutrient of the raw material for photosynthesis and chlorophyll. With enough nitrogen, the results of photosynthesis were also quite a lot. With the increase in photosynthetic yield, the growth would increase, so that the dry weight of biomass would increase too. The deficiency of N inhibited growth and decreased yield [22]. While the role of the phosphorus element was to form ATP which functions as energy in the photosynthesis process. The element of potassium as a catalyst for the translocation of photosynthesis has resulted from the source organs (leaves) to the sink organs (panicles). With sufficient potassium, the translocation of photosynthesis will be maximized so that it will increase the stover dry weight.

The grain dry weight is related to the dry weight of biomass because the more photosynthetic organs, the more photosynthetic products were stored in the organ sink [23]. The grain dry weight when harvesting had the same pattern as the dry weight of biomass, namely, with a different dose of NPK fertilizer, but the dose of human urine liquid organic fertilizer was the same, there was no difference in the grain dry weight. According to Nabavi-Pelesaraei [26], eco-efficiency of organic farming systems is positively related to yield and is systematically higher compared to conventional and limited input farming systems.

One of the causes of decreased productivity of irrigated rice fields was the low content of organic matter and an imbalance of soil nutrients due to improper fertilization [27]. Efficient fertilization was obtained from balanced fertilization, namely, the application of fertilizer to the soil to achieve the status of all essential nutrients in a balanced and optimal manner in the soil. Balanced fertilization could increase production, improve the quality of agricultural products, fertilizer efficiency, soil fertility, and avoid environmental pollution. Fertilization combination greatly affected the growth of rice crops [25].

The grain dry weight at harvest ha^-1 is related to the productive tillers number and biomass dry weight. This was identical to the research of Maruyama et al. [28]. The grain yield had the same pattern as the productive tillers number, panicle size, or grain number. Rice yield components, such as the panicles number, seed rate, and grain weight increased significantly with P fertilization.

CONCLUSION

Based on the research results and the discussion above, the conclusion showed that a combination dose of human urine and NPK fertilizer could increase the productive tillers number, straw dry weight, and grain dry weight of black cute rice. The highest grain dry weight was found at the treatment combination between human urine of 1,000 L ha^-1 and NPK of 300 kg ha^-1 and yielded the maximum grain dry weight of 8.633 t ha^-1. The study findings that the treatment combination between human urine of 1,000 L ha^-1 and NPK of 300 kg ha^-1 reaches the maximum yield of black cute rice in Litosol soil. For future research, we recommend that the treatment combination between the dose of human urine of 1,000 L ha^-1 and NPK of 300 kg ha^-1 can use in other rice varieties.

REFERENCES