13 ESAFS 2017 Thailand

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13th International Conference of the East and Southeast Asia Federation of ... aims to investigate the effect of organic amendment on GHG emission and rice ...

13th ESAFS 2017 Thailand

13th International Conference of The East and Southeast Asia Federation Of Soil Sciences (13th ESAFS) “Soil Quality for Food Security and Healthy Life”

E-proceedings 12-15 December 2017 Nong Nooch Tropical Garden, Pattaya, Thailand

13th International Conference of the East and Southeast Asia Federation of Soil Science Societies GHG EMISSION AND RICE YIELD DUE TO ORGANIC MATTER AMENDMENT ON A POOR RAINFED RICE FIELD Miranti Ariani, Rina Kartikawati and Prihasto Setyanto Indonesian Agricultural Environment Research Institute Jl. Jakenan-Jaken km 5 Pati, Central Java, Indonesia Email: [email protected], tel: (+62)295 4749044, fax: (+62)295 4749045 Abstract The addition of organic matter to the soil has proven could improved the physical, chemical, and biological soil structure. Organic matter amendments to improving soil fertility and enhancing crop productivity, may lead to GHG emission by processes such as priming effect, methanogenesis, nitrification, and denitrification. Organic matter amendment into soil supposed to influence the quantity of GHG release depends on the characteristics of the soil, water availability and O 2. This research aims to investigate the effect of organic amendment on GHG emission and rice yield in a poor rainfed rice field, which top soil has been removed and left the soil less fertile (low C, N and K). The research was conducted at Indonesian Agricultural Environment Research Institute for three consecutive rice growing season starting on rainy season (RS) 2014. The experiments were arranged in a randomized block design with four treatments (without OM as control (1) and 3 types of OM, which were (2) rice straw, (3) bio-compost, (4) compost, each in the amount of 5 t/ha) and replicated three times. Every experimental plot incorporated with inorganic fertilizer at farmers rates combined with leaf color chart. Measurements of GHG emission (CH4 and N2O) were conducted biweekly in 3 seasons (DS-RS-DS) using manually closed chamber method. The effect of different treatments were analyzed with Minitab version 16 Software, the significant effects of the treatment were examined by using a two-way analysis of variance (ANOVA). When significant differences were detected at P = 0.01 and P = 0.05, the mean values were compared by using Tukey’s pairwise comparison test. Results show that there is significant differences in CH4 emissions between treatments in those three season (p1%, whereas the ideal is > 2.5 - 4%. Organic matter is a component to apply in conservation of sustainable agricultural land resources. The addition of organic matter into the soil could lead to improve the physical, chemical, and biological fertility of the soil (Adhya et al., 1998; Cao et al. 1995). Organic matter amendments to improving soil fertility and enhancing crop productivity, may also lead to GHG emission by processes 12-15 DECEMBER 2017 NONG NOOCH TROPICAL GARDEN, PATTAYA, THAILAND

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13th International Conference of the East and Southeast Asia Federation of Soil Science Societies such as priming effect, methanogenesis, nitrification, and denitrification (Tangarajan et al, 2013). Priming effect is the stimulation of SOM decomposition by the addition of OM which can lead to CO2, CH4, and N2O emissions. Methanogenesis is the production of CH 4 by microbes (methanogens) in soil under anaerobic condition. Nitrification and denitrification, the two contrasting microbial processes in soil N cycle can lead to N2O emission. Indonesian Second National Communication (2010) stated that agriculture as a managed soil contributed for about 79% of the N2O emission and 60% of the CH4 emissions nationally. Indonesia is an agricultural country, of the 200 million ha of land territory, about 50 million ha are devoted to various agricultural activities (Statistics Indonesia 2014). Depending on the source of water and the provision of irrigation facilities, land is classified as technical irrigation areas, semi - technical irrigation areas, simple irrigation areas, village irrigation areas, inland and tidal swamp and rainfed areas. Over 50 % of rainfed areas exist in Java Island. 180.952 ha in West Java, 268.970 ha in Central Java and 240.273 ha in East Java. Rainfed area is vulnerable to drought (total annual rainfall < 1500 mm/yr), has a very low productivity, mostly because of low quality of soil (low CEC, low C-content, low N and K) therefore the use of synthetic fertilizer to improve yield are a must, and sometime becomes excessive. The rainfed field which top soil has removed even brought worse condition, left the soil in a very poor of nutrient structure, made the productivity even lower. This condition brought us to an option of using organic matter amendment. GHG emissions from paddy fields are influenced by the physiological and morphological properties of rice crops and the availability of soil carbon derived from soil organic matter and the input of fresh organic matter. The purpose of this research is to obtain information of emission of GHG emission and yield from rice field with organic matter treatment. Materials and Methods Site description The research was conducted at Research Station of Indonesian Agricultural Environment Research Institute in Pati for 3 season: dry season 2014 (march-may), rainy season 2014 (nop-jan) and dry season 2015 (march-may). The selected site represent rainfed area. The top soil was removed, so the soil left was less fertile. The soil was classified as Inceptisol according to The Soil Taxonomy System of USA. Altitude in Pati ranges from 10 to 40 m above sea level, annual mean temperature is 30oC, and annual rainfall averages 1503 mm, of which nearly 70% falls in rainy season (oct-march). As a rainfed region, 100% water supplies were provide by the rainfall, because irrigation was not practiced in the region. Experimental Design The crops were established by transplanting during the dry season and by direct seeding during the rainy season. The fields were plowed and puddled thoroughly to a 10-cm depth 5 days before transplanting. Transplanting was performed on 21 days after seedling. Ciherang rice variety was transplanted into each 5 m × 4 m plot, with 20 cm × 20 cm plant spacing and one seedling per hill. Irrigation treatments were started 5 days after transplanting, which was performed continuous flooding. Direct seeded rice was performed after fallow period. The fields were plowed and puddled 9 days before direct seeding. The seeds were inserted 4–5 cm from the soil surface, with 20 cm × 20 cm plant spacing. Continuous flooding was started 15 days after sowing. The experiments were arranged in a randomized block design with four treatments (without OM as control (1) and 3 types of OM (2) rice straw, (3) bio-compost, (4) compost in the amount of 5 t/ha) and they were replicated three times. Every experimental plot incorporated with inorganic fertilizer at farmers rates combined with leaf color chart (LCC). In first season, all plot received full of 120 kg N ha−1 (urea), 60 kg P 2O5 ha−1 (super phosphate) and 90 kg K2O ha−1 (potassium chloride), while in second and third season only received 80 kg N ha−1 (urea), 60 kg P2O5 ha−1 (super phosphate) and 90 kg K2Oha−1 (potassium chloride). Nitrogen from inorganic fertilizer were reduced in second and third season due to organic matter amendment. We were managed to use the leaf color chart to measure the quantity of N needed by the rice crops. Super phosphate were broadcast as basal fertilizer. Urea and K2O fertilizers were broadcast as three split applications at rates of 40 and 30 kg ha−1 for each application, respectively. Urea and K2O fertilizers were applied 7, 21, and 42 days after transplanting (DAT) during the DS and 22, 37 and 56 days after sowing (DAS) during the RS.

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13th International Conference of the East and Southeast Asia Federation of Soil Science Societies Gas sampling and measurement The CH4 and N2O fluxes were measured using static closed chamber and gas chromatography techniques (Wang and Wang, 2003). The closed chamber was made from 4mm thick acrylic materials consisted of two parts, a square box (without a bottom, length x width x height = 50 cm x 50 cm x 100 cm for CH4 and 40 cm × 20 cm × 30 cm for N2O) and an anchor (length x width = 50 cm x 50 cm for CH4 and 40 cm × 20 cm for N2O). There are two holes in the top of the box, one hole for placing the thermometer and the other one, is for gas sampling which equipped with rubber septum. The anchor was inserted directly 10 cm into the soil, and the square box was placed on top during sampling and removed afterwards. Four hills of rice plants were covered in each sampling CH4 chamber, and no rice plants were covered in an N2O chamber. Gas samples were collected bi-weekly. Samples were taken with 20 ml plastic syringes attached to a three-way stopcock at 3, 6, 9, 12, and 15 min following chamber closure for CH4 and 10, 20, 30, 40 and 50 min for N2O and then injected into 10 ml evacuated glass vial. The gas concentrations in the samples were analyzed in the laboratory within 24 h following sampling using a gas chromatograph (Shimadzu GC 8A equipped with a flame ionization detector (FID) for CH4 and Varian GHG 450 Series equipped with an electron capture detector (ECD) for N2O). The methods for calculating the gas flux were the same as those described by IAEA (1992):

E

273.2 Bm C V x x x t A T  273.2 Vm

where E is CH4/N2O flux (mg m-2 min-1), Bm is molecular weight of CH4/N2O (g), Vm is molecular volume of CH4/N2O at standard temperature and pressure (22,41l), ∆c/∆t is changes of CH 4/N2O concentration over time (ppm/min), V is chamber volume (m 3), A is chamber area (m 2) and T is mean air temperature inside the chamber during gas sampling ( oC). CH4/N2O flux was calculated based on the rate of change in CH4/N2O concentration within the chamber, which was estimated as the slope of linear regression between concentration and time. Soil sampling and analyses Fresh soil samples (0-20 cm) were taken from the field, it was taken before the first season and once after each harvest. Three sub samples were collected from each treatment and composited into one soil sample, mixed and placed in plastic bags after manual removal of visible plant residue and roots. Soil samples were analyzed for soil texture, total N (Kjeldahl method), total C (spectrophotography), total P and K. Statistical analyzes The effect of different treatments were analyzed with Minitab version 16 Software, the significant effects of the treatment were examined by using a two-way analysis of variance (ANOVA).When significant differences were detected at P = 0.01 and P = 0.05, the mean values were compared by using Tukey’s pairwise comparison test. Result and Discussion The average seasonal emission of CH4 and N2O from rice field with organic matter amendment from 3 consecutive growing seasons were shown at Figure 1. Average methane emissions from plot receiving straw were 320.56 kg/ha/season, the highest among treatments. Early research by Neue et al (1996) has stated this finding, that the addition of 5 t/ha of rice straw increased CH4 emissions tenfold compared to the use of urea alone. The plot receiving compost, bio-compost and without OM emitted 198.35; 155.0 and 199.1 kg/ha/season respectively. Bio-compost is compost which mixed with biochar from rice husk with 4:1 proportion. Composts used in in this research were made from crop residues and manures from feedlots. Composted OM added organic C to the soils and reported as a good source of plant nutrients. Compost application may have several of benefits: it enhances soil aggregate stability and reduces the risk of erosion (Annabi et al., 2011); increases soil porosity, thereby increasing WHC (Hargreaves et al., 2008); and releases nutrients including C and N (Benitez et al., 2003). However, most composts contain relatively low levels of nutrients (1–2% N) when compared with inorganic fertilizers (Urea N— 46%).

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CH4 emission (kg/ha/season)

13th International Conference of the East and Southeast Asia Federation of Soil Science Societies

600 500

400 300 200 100 0

Compost

Rice straw

Bio-compost

Without OM

N2O emission (kg/ha/season)

Organic matter

0.70 0.60 0.50 0.40 0.30 0.20 0.10 0.00

Compost

Rice straw

Bio-compost

Without OM

Organic matter Figure 1. Average seasonal CH4 and N2O emission by OM treatments in three consecutive rice growing season Methane emission from all plot were tended to be higher from first until third season, even the plot without OM. The emission from plot receiving rice straw was tended to be higher than those from other plot. This is occurring in every growing season. With increasing crop production, returning crop residues back to the fields plays an important role in conserving and sustaining soil productivity (Khind et al., 2004). However, addition of straw, especially in flooded rice fields has been observed to produce high CH4 when compared to un-amended soils. Addition of wheat straw with high C:N ratio depleted the plant available N which in turn reflected on the growth and activity of methanogens, resulting in more CH4 emission when compared to treatments without straw. There is significance difference in CH4 emission between rice straw treatment and other treatment. The major concern of composting is C and N-losses which decrease the agronomic value of compost and also contribute to GHG emissions (Hao et al., 2004). Organic matter amendments, especially the raw ones, were likely increased CH 4 emission, due to increasing of substrate to produce CH4 (Adhya et al, 2000; Neue et al, 1996). The main purpose of the addition of OM to the soil is to improve soil nutrient structure, in where the research conducted, top soil has removed. While improving soil nutrient to improved yield, we decide to use several OM type, to investigate the lowest GHG emitted.

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13th International Conference of the East and Southeast Asia Federation of Soil Science Societies Table 1. Significance difference on GHG emission and rice yield between treatments during three consecutive growing season CH4 N2O Yield RS

DS

DS

RS

DS

DS

RS

DS

kg/ha/season

kg/ha/season

DS

t/ha

Organic matter application Compost 5 t/ha

198.3

b

218.1

b

252.6

a

0.19

a

Rice straw 5 t/ha

320.6

a

399.1

a

445.3

ab

0.23

a

Bio-compost 5 t/ha

155.0

b

189.0

b

167.3

b

0.24

a

Without OM

172.0

b

181.7

b

195.0

b

0.16

a

ANOVA (all season) OM application

**

ns

Season

**

*

**

ns

OM application*season

0.25

a

0.41

a

2.9

a

6.6

a

3.5

a

0.23

a

0.62

a

3.1

a

6.1

ab

3.2

a

0.29

a

0.70

a

3.0

a

6.2

ab

3.4

a

0.19

a

0.48

a

2.8

a

5.8

b

2.8

a

* ** ns

*P < 0.05, **P < 0.01,. ns, not significant. Values in each column are means of five replicates. Different letters vertically indicate significant differences between means at P = 0.05 according to Tukey’s HSD-test

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13th International Conference of the East and Southeast Asia Federation of Soil Science Societies Addition of OM to flooded soils such as rice fields has been shown to enhance CH 4 emission (Table 1) which is attributed to the increased C substrate (for methanogenic bacteria) and decreased redox potential (Lee et al., 2010). The rate, type and timing of applications of OM are important management factors in determining C loss as CO2 or CH4 and N loss as N2O from the soils (Eckard et al., 2010; Weitz et al., 2001). Composition of OM differs greatly and hence varies in their effect on GHG emission during soil application (Chadwick et al., 2000). The highest, in numbers, average seasonal N 2O emission emitted from plot receiving biocompost which is 0.24 kg/ha/season. This results, unlike any other study, did not shown significance difference on N2O emission among all treatments. OM applications should contribute to N 2O emission through both nitrification and denitrification. Organic amendments provide energy for soil microorganisms which eventually increases the soil microbial biomass and denitrification rates because of decreased soil redox potential (Köster et al., 2011). Several studies have shown relationship between OM application, soil microbial properties and N2O emission and also higher rates of N loss through denitrification from soils treated with OM such as manure, composts, and plant residues when compared to un-amended or mineral N treated-soils (Dambreville et al., 2006; Walker and Shannon, 2006). Rice yield in rainfed area in rainy season (RS) shows higher value compare to dry season (DS), it is twofold high. This is commonly occur in rainfed area due to water availability and cropping method. In dry season, we apply transplanting rice, while in rainy season direct seeded rice is the best culture practice in our area. Between first and second dry season there is an improvement in rice yield. Both OM and season were had large effect on rice yield in rainfed area (P