G. PRATHIBHA*, M. SREENIVASA CHARI, T.N.V.K.V. PRASAD AND G. KARUNA SAGAR

Department of Soil Science, S.V. Agricultural College, ANGRAU, Tirupati-517 502.

ABSTRACT

A research was conducted to evaluate the yield and yield attributes of rice as influenced by biochar coated and uncoated chemical fertilizer. The experiment was done with nine treatments. 100% NK + 100% P through SSP (T1), 100% NK + 100% P through DAP (T₂), 100% NK + P through Biochar coated SSP (T₃), 100% NK + 100 P through Biochar coated DAP (T₄),100% NK + 75% P through SSP (T₅), 100% NK + 75% P through DAP (T₆), 100% NK + 75% P through Biochar coated SSP (T₇), 100% NK + 75% P through Biochar coated DAP (T₈) and Only Biochar (control) (T₉). The recommended dose of fertilizers for rice is 120:60:40 kg N: P₂O₅:K₂O ha-1. The growth parameters were recorded at different phenological stages of rice and finally yield analysis was done. Rice plants treated with biochar coated fertilizers had significantly higher grain yield (4810 kg ha-1), test weight (15.6 g), plant height (71 cm) and chlorophyll content (43) over control. Hence, it can be concluded that application of biochar coatd fertilizers to rice field is feasible to increase the grain yield under local conditions.

KEYWORDS: Biochar, Biochar coated fertilizers, yield.

INTRODUCTION

Rice (Oryza sataiva L.) is the staple food for millions people in Asia. Per capita rice consumption is around 100 kg per year. In rice cultivation, fertilizer application is an essential practice to obtain potential yield therefore effective way of fertilizer application is an important (Gamage et al., 2012) to maximize the crop production. But the excess use of chemical fertilizer causes under ground water pollution and destroys soil biota (Somaratne, 2010). Percent utilization of added phosphorus by the crops in these soils is very low compared to nitrogen and potassium. Therefore the recovery of applied phosphorus by the crops rarely exceeds 20 percent even in soils with a high total reserve phosphorus, the increasing fertilizer cost as well as maintenance of soil fertility for increased productivity warrants the use of organic manures. But the availability of organic manures decreasing progressively because of urbanization. In this context an alternate organic amendment attracting is biochar. Biochar enchaned the availability of nutrients by reducing their losses and also by changing physical chemical and biological properties of soil (Gaskin et al., 2010). Biochar improves the nutrient use efficiency results in positive impact on yield of different crops.

MATERIAL AND METHODS

The experiment was done in 2023-2024 at the Agricultural Research Station, Utukur, Kadapa, YSR district of Andhra Pradesh at 14° 46ʹ 73.0” N latitude, longitude of 78° 82′ 42.0” E and situated 138 meters above mean sea level. The climatic condition of YSR district is generally hot and humid. Rice variety used in this study was NLR 3354 which is a short duration variety (120-125 days).

Biochar from maize cobs was prepared as per the protocol developed in Department of Soil Science and Agricultural Chemistry, Agricultural Research Station, Utukur. After drying cobs in the sun, air dried maize cobs were placed in biochar kiln and covered with lid. The temperature was increased up to 450°C with the help of electrical arc. Temperature was maintained for 2 hours. Next day, the biochar was removed from the barrel and kept in open air. The prepared biochar was first grounded and passed through 0.20 mm mesh sieve. The sieved biochar was stored in polythene covers for further analysis and application. Biochar coated phosphorus fertilizers were prepared by using differernt combination of adhesives.

The experiment was was laid out in RBD with three replications and nine treatments. The treatments were as follows: 100% NK + 100% P through SSP (T1), 100% NK + 100% P through DAP(T2), 100% NK + P through Biochar coated SSP(T3), 100% NK + 100 P through Biochar coated DAP(T4),100% NK + 75% P through SSP(T5), 100% NK + 75% P through DAP (T6), 100% NK + 75% P through Biochar coated SSP(T7), 100% NK + 75% P through Biochar coated DAP (T8), and Only Biochar (control) (T9). The recommended dose of fertilizers for rice is 120:60:40 kg N: P₂O₅:K₂O per hectare.

The size of plots was 8.0 m x 2.5 m. SSP and Urea was applied to the nursery bed. Seedlings were transplanted 25 DAS. Urea was applied in three equal splits for all treatments.The recommended dose of potassic fertilizers was applied through muriate of potash (MOP) as a basal dose. The recommended dose of phosphorus was applied through SSP and DAP. The SSP and DAP coated with biochar were also applied to specified treatments. For control treatment only biochar was applied at the rate of 2 kgs per plot. Yield and yield attributes data was collected as per the standard methodology.

The data collected on various growth parameters, yield parameters and yield were subjected to statistical scrutiny by following the analysis of variance for randomized block design . Statistical significance was tested with ‘F’ test at 5 per cent level of probability. Critical difference for the significant sources of variation was calculated at 5 per cent level of significance and expressed the results as significant or non significant

RESULTS AND DISCUSSION

Plant height

The plant height of rice at 25 DAT ranged between 31 to 40 cm (Table 1.) Highest plant height ( 40 cm) was recorded with the application of 100% NK + 75% P through biochar coated DAP (T8) which was on par with all other treatments except the treatment received only biochar (T9) recorded as 31cm

At 45 DAT plant height ranged between 46 to 64 cm .The highest plant height of 64 cm was recorded with the application of 100% NK + 75% P through biochar coated DAP (T8). However the other treatments are statistically at par except the treatment (T9) which is recorded significantly the lowest plant height as 46 cm.

Table 1. Effect of fertilizer treatments on plant height of rice at different growth stages of rice

Plant height at harvest was also followed similar trend by recording maximum plant height of 71cm with the application of 100% NK + 75% P through biochar coated DAP (T8) . Significantly lowest plant height 50cm was observed in control (T9).Irrespective of their levels of application of biochar, the coated fertilizers significantly influenced the growth and yield parameters compared to control plots. This might be due to improved soil physical conditions and increased availability of nutrients which enhanced the uptake of nutrients, resulting in improved the plant height through biochar. Similar findings were found by Jangir et al.(2017) and Lai et al.(2024)

Chlorophyll content

SPAD readings of rice recorded at 25 and 45 DAT and data was presented in Table 2. The SPAD chlorophyll readings of rice at 25 DAT ranged between 22 to 37 while at 45 DAT are ranged between 33 to 43 SPAD units . The highest SPAD meter reading 37 was observed with the application 100% NK + 75% P through biochar coated DAP (T8) , which is on par with T1, T4, T2, T5, T7 and T3 recorded 36, 36, 35, 35, 34, and 32 respectively . Significantly the lowest SPAD meter reading of 22 was recorded in control treatment (T9).

At 45 DAT , highest SPAD meter reading of 43 was recorded with the application 100% NK +75% P through DAP + Biochar (T8), which is on par with the other treatments and significantly the lowest SPAD meter reading of 33 was recorded in control. This is due to biochar improved magnesium concentration which is an important element and an integral part of the chlorophyll molecule which improves the chlorophyll concentration resulted increased SPAD readings. Similar results were reported by Lehmann et al. (2019) and Effendy et al. (2020).

Grain yield

Grain yield of rice ranged between 2008 to 4810 kg ha-1 and data was presented in (Tables 3.)The fertilizer treatments tried in the experiment recorded appreciable variation in the grain yield of rice. The treatments received 100% NK + 75% P through Biochar coated SSP (T7 ) , 100% NK + 100% P through Biochar coated DAP (T4 ) and 100% NK + 100% P through Biochar coated SSP (T3 ) recorded significant and statistically at par grain yield of 4810, 4793 and 4765 kg ha-1 respectively. However, the treatments received 100% NK + 100 % P through SSP (T1) and 100% NK + 75% P through

Table 2. Effect of fertilizer treatments on SPAD Chlorophyll content of rice

Table 3. Effect of fertilizer treatments on grain, straw yield and test weight of rice

Biochar coated DAP (T8) recorded 4277 and 4203 kg ha-1 respectively. Significantly lowest grain yield of 2008 kg ha-1 was recorded in control. Increased nutrient status by supplementation through chemical fertilizers played a significant role in higher yield. The result clearly indicated that the non fertilized soil had a nutrient limitation as expected due to its inherent low CEC and organic carbon content Zhang et al .(2021), Chan et al.(2021) and Gong et al. (2024).

Straw yield

Rice straw yield was ranged between 2979 to 4123 kg ha-1 (Tables 3). All the treatments tried in the experiment were found to be on par except except treatment T9 which is recorded statistically lowest straw yield of 2979 kg ha-1. Biochar coated fertilizers increased the dry matter production by timely supply of phosphorus. Similar results were reported by Yadav et al. (2018), Coa et al.(2021) and Khan et al . (2024).

Test weight

Test weight of rice grain ranged between 15.6 to 14.7 g (Tables 3.)Shows test weight of 15.6g was recorded with the application of 100 % NK+ 75 % P through Biochar coated SSP (T7) . The lowest test weight of 14.7g was recorded in control treatment (T9). Increase in grain and straw yield tend to increase in weight of 1000 grains. Similar results were reported by Mishra et al. (2017)and Singh et al. (2021).

The study revealed that the application of biochar coated fertilizers in rice crop showed better crop performance during their growing periods. The results revealed that applying biochar coated fertilizers alone rather than chemical fertilizers improves the yield attributes and increases the grain and straw yield.This finding enriches the understanding on the adoption of biochar coated fertilizers in rice production. Further studies are needed to determine how biochar coated fertilizers effect on soil and physiological processes for producing yield .

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