Improvement of Soil Fertility and Crop Production through Direct ...

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ScienceDirect Procedia Engineering 83 (2014) 336 – 343

“SYMPHOS 2013”, 2nd International Symposium on Innovation and Technology in the Phosphate Industry

Improvement of Soil Fertility and Crop Production through Direct Application of Phosphate rock on Maize in Indonesia Husnaina*, S.Rochayatia, T. Sutriadia , A. Nassirb and M. Sarwanic a

Indonesian Soil Research Institute, ICALRD, Jl. Tentara Pelajar No. 12 Cimanggu,16114, Bogor Indonesia b OCP S.A, 2-4, Rue Al Abtal-Hay Erraha-20200, Casablanca-Morocco c Indonesian Center for Agricultural Research and Development, Jl. Tentara Pelajar No. 12 Cimanggu, 16114, Bogor Indonesia

Abstract Most of Indonesian agricultural soils are acidic and low in both total and available phosphorus particularly. The major nutrient constraint in these soils is P and responses to both N and K are poor unless P deficiency has first been corrected. Correction of P deficiency therefore constitutes a major part of improving fertility of acid soils. Phosphate rock is recommended for application to acid soils where phosphorus is an important limiting nutrient on plant growth. This problem faces most acid soils in Sumatra and Kalimantan. We conducted a study of the effect of reactive phosphate rock for Maize on an Ultisol in Pleihari, South Kalimantan Province. The experiment was carried out in farmer fields for six cropping season. The objectives are to evaluate direct application of reactive phosphate rock (RPR) for Maize, its combination with manure and agronomic effectiveness. Reactive phosphate rock improved soil fertility and maize crop productivity. Moroccan RPR contained the highest citric acid extractable P2O5 among other phosphate rock tested and also the most effective in improving maize yield. In addition, the residual effect of phosphate rock in supplying plant with P for up to six cultivation years was demonstrated. However, although phosphate rock is cheaper than SP-36, farmers did not adopt this technology yet. Through collaboration research between The OCP and ISRI (Indonesian Soil Research Institute), a more comprehensive study on the potential effect of direct application of Reactive Phosphate Rock from OCP MOROCCO, on Maize is being conducted.The overall objectives are to evaluate direct application of Reactive Phosphate Rock for Maize and find out the best application rate and method of Rock Phosphate for Maize.

© 2014 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license © 2014 The Authors. Published by Elsevier Ltd. (http://creativecommons.org/licenses/by-nc-nd/3.0/). Peer-review under responsibility of the Scientific Committee of SYMPHOS 2013. Peer-review under responsibility of the Scientific Committee of SYMPHOS 2013 Keywords: reactive phosphate rock, phosphate rock, direct application, acidic soils, P deficiency.

1. Introduction Most of Indonesian agricultural soils are acidic and low in both total and available phosphorus. According to Mulyani et al.[1], about 104 million ha (68%) from total 148 million ha are acidic and mostly found in Sumatra, Kalimantan and Papua Island. High demand on food crops due to population pressure increased the use of marginal soils. Therefore, expanding of newly developed agricultural area is addressed to these islands. Approximately 47.1 million ha are available as new agricultural land (with slopes of 0 to 15%). In addition, Adiningsih and Karama [2] reported that 15 to20 million ha are potentially suitable for the cultivation of tree crops or estate crops.

* Corresponding author. Tel.+ 62-251-8321608; fax: +62-251-8321608 E-mail address: [email protected]

1877-7058 © 2014 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license

(http://creativecommons.org/licenses/by-nc-nd/3.0/). Peer-review under responsibility of the Scientific Committee of SYMPHOS 2013 doi:10.1016/j.proeng.2014.09.025

Husnain et al. / Procedia Engineering 83 (2014) 336 – 343

Acid soils such as the Ultisols and Oxisols in South Kalimantan Province are deficient in phosphorus, an essential macronutrient in all biological organisms, according to the Sharpley and Rekolainen [3]. In these soils, P availability is reduced through adsorption by aluminum (Al) and iron (Fe) oxides and by precipitation with soluble Al and Fe as reported by Sanyal and De Datta [4] and Rhue and Harris [5]. Reddy et al. [6] found that phosphorus adsorbs to mineral surfaces and once all surface sites are filled then P begins to diffuse into the particle by absorption. In addition Bolan et al. [7] reported that sorption processes are highly depending on pH while process rates decrease with time. Low solubility of phosphate rock (PR) has discouraged its recommendation for direct use as a source of P for crops. However, it is proven to have beneficial effects on tree plantation grown on acid soils where soil acidity slowly releases plant available P. Reactive phosphate rock is the more suitable phosphate rocks where its chemical composition allows rapid dissolution in the soil solution. The uniform application of finely ground phosphate rock is not easy. Maene [8] stated that since the importance of phosphate in crop production was recognized, the potential for using the rock without chemical processing has gained more attention. According to FAO [9], for the past 50 years, considerable knowledge regarding the factors affecting the agronomic effectiveness of PR for direct application has seen accumulated. Some PRs contain also accessory minerals that may provide micronutrients to improve plant growth. However, availability of PR in the local market also became another challenge. According to Maene [8], in case of Indonesia, PR is mostly used for tree plantation and not available for food crop farmers in Indonesia. In recent years, attention has been focused on PR direct use as reported by IFDC [10] and Sanchez et al. [11]. Ahn [12] reported that the main interest of the use of PR is its relatively low cost compared with the processed P fertilizers, and to its effect both in supplying P and long term residual effect that increases efficient use of this slow P fertilizer. In addition, Mnkeni [13] discovered that other element contained in PR, such as Ca, is an advantage to improve soil chemical and physical characteristics and also to contribute to plant nutrition. This study was conducted to: (i) monitor the effect of the application of phosphate rock combined with manure on soil chemical properties, with particular emphasis on P availability and maize yield; and (ii) compare the agronomic effectiveness of PR combined with manure in relation to single superphosphate 36% P2O5 (SP-36). The results of this study are used as the basic recommendation for PR application in acid soil for Maize in Indonesia. Through collaboration research between The OCP and ISRI (Indonesian Soil Research Institute), a study on the potential effect of direct application of Reactive Rock Phosphate from OCP MOROCCO, in Maize is being conducted.The ongoing research is just started on January 2013. The overall objectives are to evaluate direct application of reactive phosphate rock for maize and find out the best application rate and method of phosphate rock for Maize. 2. Methodology 2.1.

Site description

The study was carried out in two farmer fields in Sukaramah village, Pleihari, South Kalimantan Province for six consecutive maize cropping seasons. In general, maize is the dominant crop commonly cultivated twice a year. The dominant cropping pattern in the study area is maize-maize-fallow (50%) or rosella-fallow (15%). The soil used was an Ultisols, derived from claystone and/or sandstone of Dahor formation. Dahor formation (TQd) is composed of sedimentary rocks of the Tertiary-Quarternary period, and consisting mainly of claystone and few sandstone. In general, the soil is moderately deep, slightly coarse textured (loamy), exhibiting yellowish color, and often has layers of gravel at different depth. The experimental site is nearly flat around the rivers Sabuhur in Sukaramah. The site has a monsoon climate, with mean annual rainfall of 2,584 mm, and mean daily air temperature of 27.1 o C. Wet season occurs from November to April, and dry season from May to October. The site belongs to B-rainfall type, and a C2agroclimate zone with 5-6 wet months and 2-3 dry months. 2.2. Field experiment The on-farm trial is conducted at farmers fields with plot size about 2,000 m2 for each treatment. The selected trial was conducted on 2 farmer fields. Four sources of PR: Tunisia PR, Morocco PR, Senegal PR, and Jordan PR were tested, compared with farmer’s practice. The treatments include Farmer practice(A); PR 1 t ha-1 + Manure 1 t ha-1 (B) and PR 1 t

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ha-1 + Manure 2 t ha-1 (C). One ton of PR (containing about 300 kg P2O5 per hectare) was used to overcome soil P “fixation” and to supply sufficient P for about three consecutive years (6 cropping seasons). The rate of PR applied was based on the result of preliminary study [14]. Urea and KCl fertilizers were applied as recommendation rates considering soil nutrient status (Table 1). The on farm trial was conducted for six cropping season started from wet season (WS) in November 2001 until dry season (DS) in August 2004. The indicator plant used in this experiment was hybrid maize C-7. To promote maximum contact between roots and enriched soil, the PR was incorporated into the soil. Table 1. The average application of production input for maize per hectare at P Recapitalization with PR in South Kalimantan during six cropping seasons (WS.2001/2002 – DS.2004).

Material Seed (kg) PR (kg) Manure (kg) Urea (kg) SP-36 (kg) KCl (kg)

Farmers practice (A)

PR 1 t ha-1+Manure 1 t ha-1 (B)

PR 1 t ha-1 + Manure 2 t ha-1 (C)

15 0 1.540 340 11 100

15 1.000 1.000 300 0 100

15 1.000 2.000 300 0 100

Notes: Manure used in this study is chicken manure

Two composite soil samples were taken at each plot before and after harvest for each treatment. The soil samples were analysed for texture, pH, organic matter content, CEC, base saturation, total P 2O5 (HCl 25%) and available P2O5 (Bray I), acid saturation, Fe and Zn content in the soil laboratory of the Indonesian Soil Research Institute (ISRI). Super imposed trial An additional study was done to confirm the dynamic of P by applying PR and single superphosphate (SP-36). The experimental design in this study was split-plot with three replications. Main plots are manure and without manure, while the sub plots are 1). without P fertilizer; 2). 300 kg ha-1 SP-36; 3). 1 ton ha-1 Jordan PR +; 4). 1 ton ha-1 Morocco PR ; 5). 1 ton ha-1 Senegal PR; and 6). 1 ton ha-1 Tunisia PR. Plot size was about 6 m x 8 m. The maize variety used in this experiment was Bisi-2. Fertilizer of single super phosphate (SP-36) and phosphate rock was applied as broad cast into the soil a week before planting. Laboratory and statistical analyses Chemical analysis of the soil samples was carried out using routine procedures as explained in Bray and Kurtz [15], Chien [16], ISRIC [17] and USDA [18]. The data collected was analysed using SAS. 3. 3.1.

Results and Discussions Soil characteristics

The soil used in field experiment was acidic, low in fertility and exhibited a high P adsorption capacity (Table 2). Soil textures are clayey with low organic carbon content, low base saturation and low CEC. The low soil pH (4.4) and available P (4 - 4.8 mg P2O5 kg-1) levels were a clear indication that the soils required supplemental P. As reported in Okalebo et al. [19], The available P was far below the critical available P value of 10 mg P kg෥1 required for optimum growth and yield of a maize crop.

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Husnain et al. / Procedia Engineering 83 (2014) 336 – 343 Table 2. Surface soil properties (0-20 cm) in Pelaihari, Tanah Laut District, South Kalimantan Province Soil characteristic

Farmer 1Ultisol

Farmer 2

Soil order Texture

Clay

Clay

pH (H2O 1:1)

4.4

4.4

C-organic (%)

1.13

1.97

P2O5 (mg/100 g) HCl 25 %

13

19

P2O5 Bray 1 (mg kg-1)

4.0

4.8

CEC cmolc kg-1

10.69

9.00

Base saturation (%)

15

25

Al3+ (me/100 g) KCl 1N

1.39

0.66

H+ (me/100 g) KCl 1N

0.11

0.23

Al Saturation (%)

45.13

20.89

Fe (ppm) DTPA

41.51

38.86

Zn (ppm) DTPA

0.80

0.71

Maize grain yields The result of maize yield are presented in Figure 1. Average maize yield ranged from 5.05 to 7.3 t ha -1 at wet season and from 1.62 to 3.26 t ha-1 at dry season. It was clearly shown that yield at dry season decreased more than 50% compared to wet season due to less water availablity. The highest yield for each planting season (PS) was found at treatment C, combination of RP (1 t ha-1) and Manure (2 t ha-1) although there was not significantly different than treatment B. This means applying phosphate rock combined with manure could improve maize yield on upland acid soil (Fig. 1). Similar result was reported by Waigwa [20], showing that combining phosphate rock with the organic materials improved its relative agronomic effectiveness for maize. Application of 1 t ha-1 PR at first season resulted high residue effect until sixth planting season for both wet and dry seasons. This indicate that PR was subsequently releasing P2O5 for supplying maize growth.. Application of PR+Manure was significantly increasing maize yield compared with farmer practice where no PR was applied. The result obviously showed that slow release of reactive phosphate rock contributed in increasing maize yield. As comparison, Ndung’u [21] reported that applying 60 kg P ha−1 on an acid soil in Kenya was found sufficient for only three cropping seasons. Low rate of PR application was inefficient compared with high rate of PR application. The application cost and time saving is the farmer benefit when applying PR once at first planting season at high rate.

Figure 1. Yield of maize at dry (DS) and wet season (WS) under Ultisol in Sukarmanah, Pleihari, South Kalimantan (A: Farmer practice, 1 t ha-1, C: RP 1 t ha-1+Manure 2 t ha-1; PS: planting season)

B: RP+Manure

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Figure 2. Yield of maize at dry and wet season (DS and WS) treated with different types of Phosphate rock under Ultisol in Sukarmanah, Pleihari, South Kalimantan (PS: Planting season)

In this study we compared four types of high quality RPR for six cropping seasons. The results are shown in Figure 2. There was no significant differences on maize yield among the four types of RP tested. The relatively high yield obtained with Morocco PR (PS3 and PS4 seasons) is probably related to its chemical characteristics where citric acid soluble P (15.13%) and CaO (30.36%) content were the highest compared to other PR used in this study. Phosphate rock is most known as slow released fertilizer, but reactive rock phosphate as we used in this study could give similar result of maize yield at first planting season and showed its benefit in improving yield at second and continuously until sixth planting season. Based on this result, we would like to confirm this result using Morocco phosphate rock on Oil Palm and Maize under collaboration between the OCP Group and ISRI located in Sumatra and Kalimantan Islands, starting from January 2013. A super imposed study was conducted in the study site to compare the effect of highly water soluble P (SP-36) and slow release P source (phosphate rock) and to study the effect of manure in combination with PR (Fig. 3). The result shows that PR could supply P relatively similar with SP-36 after second cropping season. The result showed that P was absolutely required to improved yield. This implies that application of PR would benefit farmer at least from second planting season. The extractable soil P at second cropping season when no addition of PR was made, strongly demonstrated that PR continued to decompose and release P (residual effect) into the soil. As shown in Figure 3, combination of PR with manure was able to increase maize yield about 5 to 30 %. This study shows better the effect of applying manure that was not appearing clearly in on farm trial. Although, the interaction between PR and organic matter and consequent effects in acidic soil are not fully understood, its benefit was confirmed. Increase of dissolved P probably explains the enhanced growth and P concentration in plant, as explained by Alloush [22] (Fig. 4).


Figure 3. The comparison of different source of P (water soluble P) (SP-36) and citric acid soluble P (phosphate rock) at Ultisol in Pleihari, South Kalimantan (WS: Wet season, DS: Dry season, PS: planting season)

Figure 4. P dynamics under application of PR and manure in the study site (WS: wet season, DS: dry season).

Financial analyses A financial analysis of the farming practices during experiment is given in Table 3. The farmer income during dry season 2 and 4 was negative due to insufficient water for irrigation. While in cropping season 1, 3, 5 and 6 farmer gets benefit as shown in R-C ratio ≥1. Interestingly, at the last cropping season, although no sufficient water irrigation available, the maize yield showed high yield and financially benefit the farmer. This was in part due to residual effect of phosphate rock applied at first cropping season. Economic analysis of wet season or third planting season showed that the application of PR increased the farmer’s income about 571% compared to the farmer’s practice. This high income was surprising the farmers and increased phosphate rock demand. Farmers decided to adopt new technology mostly by self experience and when it works, they will disseminate this technology among other farmers. That is the reason why on farm research is found the most effective way to disseminate and educate farmers. Similar result was found in acid soil in Kenya reported in Kifuko et al. [23] where a single application of chicken manure (2 t ha෥1) combined with PR at 60kg P ha෥1 gave the highest incremental net benefit equivalent to US$ 657 ha −1 during the three maize cropping seasons.

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Adiningsih and Fairhurst [14] reported that in the year of 2000, the price of 1,000 kg PR is equivalent to 280 kg TSP and 700 kg of lime, pointing to the current economic superiority of the PR option. However, the adoption of rock phosphate in Indonesia is still limited to the plantation/estate. The most limiting factor in using phosphate rock is its availability in the market. Table 3. Financial analyses of maize yield from 6 planting season at Ultisol, Pleihari, South Kalimantan Planting season I

II

III

IV

V

VI

Treatment

Material Cost

Income

R-C

($)/ha

($)/ha

Ratio

A

157.81

164.07

1.50

B

263.38

98.38

1.21

C

292.79

90.12

1.18

A

157.38

-29.79

0.89

B

132.80

12.64

1.06

C

162.21

5.16

1.02

A

180.03

43.54

1.12

B

134.71

215.26

1.61

C

167.65

292.30

1.71

A

141.91

-27.90

0.89

B

135.97

52.04

1.21

C

168.91

28.30

1.10

A

188.19

95.13

1.24

B

155.98

198.70

1.51

C

186.58

245.67

1.58

A

164.92

179.69

1.63

B

142.14

265.49

1.98

C

175.08

323.88

2.04

Note: A (Farmer practices), B ( PR 1 t ha-1 + Manure 1 t ha-1) and C (PR 1 t ha-1 + Manure 2 t ha-1), R-C ratio = return: total cost; 1 $= Rp.8.500, -

Conclusion Under P-deficient acid soil conditions in South Kalimantan, significant positive responses to phosphate rock application were observed for Maize. The significant increase in the maize yield was found when phosphate rock was combined with organic material such as manure for 1 or 2 ton ha-1. This study suggests that phosphate rock could be an effective and efficient P source of fertilizer especially its residual effects. Morocco phosphate rock appears to be an effective source of P in this regard. Acknowledgements The authors would like to express their appreciation to Insitut Mondial du Phosphate (IMPHOS) for financially supporting this researchand The OCP Group for supporting the ongoing research. We are indebted to researchers and technicians who work for this project especially Imam Purwanto, Saprin, Rahmat Hidayat dan Agus Sudaryanto. Special thanks also go to the farmers who allowed us to use their farms for about six seasons. References [1]

Mulyani A, Hikmatullah, and Subagyo H. Characteristics and potency of upland acid soils in Indonesia. Proceeding of the Symposium Nasional Pendayagunaan Tanah Masam. Soil Research Institute. 2004

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