IOP Conference Series: Earth and Environmental Science PAPER • OPEN ACCESS Dynamics of soil physical and chemical properties within horizontal ridges-organic fertilizer applied potato land To cite this article: Krissandi Wijaya et al 2019 IOP Conf. Ser.: Earth Environ. Sci. 255 012024 View the article online for updates and enhancements. This content was downloaded from IP address 172.245.209.181 on 22/06/2019 at 15:35 ICLAS-SURE IOP Conf. Series: Earth and Environmental Science 255 (2019) 012024 IOP Publishing doi:10.1088/1755-1315/255/1/012024 Dynamics of soil physical and chemical properties within horizontal ridgesorganic fertilizer applied potato land Krissandi Wijaya*1), Purwoko Hari Kuncoro1), and Poppy Arsil1) 1) Department of Agricultural Technology, Faculty of Agriculture, Jenderal Soedirman University, Jl. dr. Soeparno No. 61, Karangwangkal, Purwokerto 53123, Central Java, Indonesia E-mail: kwijaya77@gmail.com Abstract. Although the horizontal (contour) ridge has been shown to be significantly effective in reducing erosion within potato land in our previous study, it tends to enhance waterlogged in the soil by which the productivity of crop may be decreased. Beside the availability of organic materials, the dimension of ridge may also affect the waterlogged. However, their impact on the soil properties have been yet less paid attention. This study was aimed to identify the effect of horizontal ridges dimensions on soil physical and chemical properties over organic fertilizer applied potato land. Totally 9 potato plots of 3x3 m2 were prepared in Serang village, Purbalingga with three different dimensions and replications of the horizontal ridges: 30x 30x30 cm3 (HR30), 30x40x30 cm3 (HR40), and 30x50x30 cm3 (HR50). Petroganik (C-org: 12.5%, C/N ratio: 10-25) fertilizer of 20 ton ha -1 was applied into these plots. Soil samples were collected from each plot at 0, 8, 35, 71, and 91 days after planting using 100-cc ring samplers. The physical (volumetric water content, dry bulk density, permeability) and chemical (total-N, total-P) properties of soil were then analyzed in laboratorium using gravimetric and Kjeldahl-Colorimetric method, respectively. The results showed that the soil volumetric water content and dry bulk density increased with increasing the ridges dimensions, of which the highest values of 0.450 cm3cm-3 and 0.730 gcm-3 each were found in HR50. Conversely, the soil permeability decreased with increasing the ridges dimensions, of which the highest value of 0.027 cms-1 was encountered in HR30. The soil total-N and total-P contents were slightly fluctuated, of which the highest values of 4.111 and 2.213 tonha -1 each were seen in HR40. Thus, the horizontal ridge with 40 cm-width might be the most suitable for the organic potato cultivation. Keywords: Horizontal ridge dimension, organic fertilizer, potato land, soil properties dynamics, waterlogged condition 1. Introduction Potato has been known as an economically promising commodity in over the world. In tropical region, the crop is usually cultivated in highland areas using vertical (slopping) ridge system with intensive chemical fertilizers and pesticides applications [1]. Such practices, however, may accelerate land and environment degradation. As reported by [2] application of the vertical ridge system on potato lands at the upper stream of Serayu watershed, Central Java, Indonesia has been found to cause severe runoff and soil losses, i.e., 1,358 – 1,435 m3 ha-1 year-1 and 56.24 – 145.75 ton ha-1 year-1, respectively. Furthermore, this also has contributed to sedimentation at Serayu river about 4.3 million m3 year-1 and water contaminated about 100 mg L-1 COD and 16.50 mg L-1 BOD [3]. Instead of the vertical ridge system, the horizontal (contour) system has been introduced for potato lands [2]. The latter has been found to be significantly effective in reducing runoff and soil losses, i.e., 17 – 34 % and 31 – 73 %, respectively, compared to the former [4]. Nevertheless, less crop yield was noticed, in which the horizontal ridge system might decrease crop productivity about 12% [1] and 23% [2] in rainy season. This was owed to the possible water logging nearby the ridges that might alter soil aeration and drainage conditions [5,6,26]. On the other hand, organic fertilizer is well-known as soil amendments and usually applied to improve the soil physical and chemical properties. The organic fertilizer may enhance water retention, aeration status, and nutrients available for plant [7,23]. Besides, dimension of ridge may affect the soil water content and movement [8,9], hence the waterlogging within the ridge. Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Published under licence by IOP Publishing Ltd 1 ICLAS-SURE IOP Conf. Series: Earth and Environmental Science 255 (2019) 012024 IOP Publishing doi:10.1088/1755-1315/255/1/012024 Nevertheless, a potential of the organic fertilizer and ridge dimension to overcoming the entailing problems of the possible occurring waterlogging upon the horizontal-ridge system has yet been paid less attention. Accordingly, this study aimed to clarify efficacy of the organic fertilizer and ridge dimensions on the improvement of soil physical and chemical properties over horizontal-ridge system of potato land. The results were then expected to have significant impact on improving potato crop productivity as well as maintaining land and environmental conservation. 2. Materials and Method 2.1. Land preparation The research site was located at Serang agricultural highland in Central Java province of Indonesia (7°14’31’’ S, 109°16’50’’E) with a typical soil of Andisol (Table 1). A horizontal-ridge system was developed over 9 targeted plots of 3 x 3 m2 each (Fig. 1B) and varied within various dimensions, i.e. 30 x 30 x 30 cm3 (HR30), 30 x 40 x 30 cm3 (HR40), and 30 x 50 x 30 cm3 (HR50) (Fig. 1A). Upon these plots, organic fertilizer (Petroganik, a local commercial product: 12.5% C-organic, 10-25 C/N ratio) was applied with the rate set for 20 ton ha-1 in order to meet equivalent rate of NPK with those of the inorganic fertilizer usually used. Of the each plot, 1 m height plastic sheet, of which 20 cm was embedded into the field, was vertically installed along the plot edges. 30-cm ridge width 40-cm ridge width 50-cm ridge width A Note: 1 Potato crops 2. Horizontal ridges with different dimensions, 3. Sampling points, 4. Plastic sheets (plot border), and 5 Sediment collectors B Figure 1. Schematic diagram of experimental plot. Table 1. Physical and chemical properties of Serang’s Andisol soil Parameter Dimension Value Texture Loam Sand g g-1 37.44 Silt g g-1 48.18 -1 Clay gg 14.38 Filed capacity % 44.07 Permanent wilting point % 19.83 C-organic % 5.60 pH 4.96 Total-N (Available-N) % (ppm) 0.52 (57.16) Total-P (Available-P) % (ppm) 0.49 (0.61) 2 ICLAS-SURE IOP Conf. Series: Earth and Environmental Science 255 (2019) 012024 IOP Publishing doi:10.1088/1755-1315/255/1/012024 2.2. Soil sampling and measurement Undisturbed soil samples at 10, 20, and 30 cm depth were taken nearby the horizontal ridges of each plot using 100 cm3 core samples. The samples were weighed to determine soil wet-bulk density ( t) and then water saturated for saturated hydraulic conductivity ( Ks) measurement using falling head method. The samples were finally oven-dried at 105 oC for 24 hours to determine soil mass-wetness (w) and dry-bulk density ( b), by which the volumetric-water content () could be calculated from. The disturbed soil samples were also taken from the similar locations at the same depth and time as the undisturbed soil samples collection. The samples were analyzed to determine soil total-nitrogen (TN) and total-phosphorus (TP) using Kjeldahl and Colorimetry, respectively. 2.3. Data analysis The t, w, b, and  were calculated using the following equations, respectively. 𝜌𝑡 = 𝑤= 𝑀𝑡 𝑉𝑡 (1) 𝑀𝑡 −𝑀𝑠 𝜌𝑏 = (2) 𝑀𝑠 𝑀𝑠 (3) 𝑉𝑡 𝜃 = 𝜌𝑏 𝑤 (4) Where, Mt is the total mass of soil sample (g), Ms is the dry mass of soil sample (g), Vt is the total volume of soil sample (cm3). The Ks was calculated using the following equation. 𝐾𝑠 = 𝐻 2.3𝑎𝐿 𝑙𝑜𝑔 1 𝐻2 𝐴∆𝑡 (5) Where, a is the cross-sectional area of inputted water pipe, L is the height of soil sample, A is the crosssectional area of soil sample, and t is the time lag between H1 (upper level of inputted water) and H2 (lower level of inputted water). The soil physical ( t, w, b,, and Ks) and chemical properties (TN and TP) of each ridge dimension (plot) and sample location were averaged and plotted graphically. Both properties were correlated one to another to analyze their correspondences as well as to find most appropriate treatment for sustainable cultivation in tropical region. 3. Results and Discussion 3.1. Soil volumetric-water content () As shown in Fig. 2A, the average  values within the horizontal ridges-organic-fertilizer applied potato land tended to increase throughout a cultivation period. The highest  values of 0.48 – 0.51 cm3 cm-3 was reached at 71 days after planting (DAP), while the lowest  values of 0.34 – 0.41 cm3 cm-3 was encountered at 35 DAP, regardless ridge dimensions. This was presumably related to rainfall event, in which the  values increased as the rainfall rates increased and vice versa [10,11]. Besides, the high silt content and organic matter in typical Loamy soil observed might also contribute to increasing soil waterholding capacity [12,13]. Among three ridge dimensions applied, the 50-cm ridge width had highest  value, followed by the 40-cm and 30-cm ridge widths, i.e., 0.45, 0.41, and 0.40 cm3 cm-3, respectively. (Fig. 2B). This indicated that increasing the ridge dimensions might enhance water entrapment or waterlogged within ridge profile [14]. However, these  values were considerably similar, since their differences were less than 5 % [15]. 3 A IOP Publishing doi:10.1088/1755-1315/255/1/012024 Vol. water content (cm3 cm-3) Rainfall (mm) Vol. water content (cm3 cm-3) ICLAS-SURE IOP Conf. Series: Earth and Environmental Science 255 (2019) 012024 B Rainfall Day after planting (DAP) Width of ridge (cm) Figure 2. Soil volumetric-water content within various dimensions of the horizontal ridges. 3.2. Soil dry-bulk density (b) Dry bulk density (g cm-3) Rainfall (mm) Dry bulk density (g cm-3) There was a tendency for the average b values within the horizontal ridges-organic-fertilizer applied potato land to decrease over a cultivation period (Fig. 3A). The highest and lowest b values were found at 8 and 91 DAP, i.e., 0.74 – 0.78 and 0.59 – 0.66 g cm-3, respectively. The rainfall event was presumably affected the b, in which higher rainfall rates might increase the b values thought soil particles detachment and pore clogging [16,24]. Decreasing the b values might be also affected by the crop roots development, by which the soil aggregation or porosity might be improved [17]. B A Rainfall Day after planting (DAP) Width of ridge (cm) Figure 3. Soil dry-bulk density within various dimensions of the horizontal ridges. The horizontal ridge with 50-cm width had highest b compared to that with 40-cm and 30-cm widths, in which their values were 0.73, 0.71, and 0.69 g cm-3, respectively (Fig. 3B), although the differences were considerably insignificant [15]. Higher the b value as the ridge become wider was presumably related to higher the corresponded  value, wider the ridge, more the water entrapped and denser the soil. This was related to the soil particle dispersion and pore clogging caused by waterlogged phenomena [12]. Besides, the less availability of soil organic matter might corroborate the results [17]. 3.3. Soil saturated-hydraulic conductivity (Ks) The average Ks values within the horizontal ridges-organic-fertilizer applied potato land tended to fluctuate throughout a cultivation period (Fig. 4A). The highest Ks values of 0.032 – 0.035 cm s-1 were encountered at 35 DAP, while the lowest Ks values of 0.013 – 0.015 cm s-1 were found at 71 DAP. 4 ICLAS-SURE IOP Conf. Series: Earth and Environmental Science 255 (2019) 012024 IOP Publishing doi:10.1088/1755-1315/255/1/012024 Sat. hydraulic conductivity (cm s-1) Rainfall (mm) Sat. hydraulic conductivity (cm s-1) These Ks values corresponded with the  and b values, in which higher the Ks, higher the and lower the b [12,19,20]. Rainfall A Day after planting (DAP) B Width of ridge (cm) Figure 4. Soil saturated-hydraulic conductivity within various dimensions of the horizontal ridges. More specifically, the Ks values tended to decrease with increasing the ridge widths (Fig. 4B). The 50-cm ridge width had the lowest Ks value compared to the 40-cm and 30-cm ridge widths, i.e., 0.023, 0.025, and 0.027 cm s-1, respectively, although these values were not significantly different. The decreasing Ks value was closely related the increasing corresponded b value, in which higher the b value might reduce Ks value as well as percolation rate [22]. 3.4. Soil total-nitrogen (TN) Total-N (kg ha-1) Rainfall (mm) Total-N (kg ha-1) In general, the average TN values within the horizontal ridges-organic-fertilizer applied potato land tended to decrease over a cultivation period (Fig. 5A). The highest and lowest TN values were found at 0 and 91 DAP, i.e., 4.22 – 5.23 ton ha-1 and 3.08 – 3.23 ton ha-1, respectively. This might be related to the crop development that consumed more nitrogen especially at the initial stage [17,25]. Besides, the high rainfall induced the increase in  values and the decrease in b and Ks values might affect more nitrogen loss through runoff or percolation [16,21]. More specifically, the 40-cm ridge width, however, was better in maintaining soil TN compared to the 30-cm and 50-cm ridge widths, at which after 35 DAP it shown to be slightly increased. Rainfall B A Width of ridge (cm) Day after planting (DAP) Figure 5. Soil total-nitrogen within various dimensions of the horizontal ridges. Regarding the ridge widths, there was a tendency for the TN value to increase from 3.99 ton ha-1 (30cm width) to 4.11 ton ha-1 (40-cm width), but then decrease to 3.66 ton ha-1 (50-cm width) (Fig. 5B), in 5 ICLAS-SURE IOP Conf. Series: Earth and Environmental Science 255 (2019) 012024 IOP Publishing doi:10.1088/1755-1315/255/1/012024 which the values of two latter ridge widths were considerably insignificant. Among others, the highest capability of 40-cm ridge width in entrapping water and reducing runoff might be a reason for this results. Besides, this might be also related to higher the , b, and Ks within the 40-cm ridge profile compared to the 30-cm and 50-cm ridge widths. These higher values might then stimulate increasing water entrapment and percolation within the former ridge profile, hence reducing run off [22,23]. 3.5. Soil total-phosphorus (TP) Similar to TN, the average TP values within the horizontal ridges-organic-fertilizer applied potato land Total-P (kg ha-1) Rainfall (mm) Total-P (kg ha-1) generally tended to decrease throughout a cultivation period (Fig. 6A), in which the highest and lowest values were encountered at 0 and 91 DAP, i.e., 2.39 – 3.85 ton ha-1 and 0.93 – 1.37 ton ha-1, respectively. The nutrient uptake during crop development might trigger the phosphorus release from soil [17]. This was presumably stimulated by high rainfall rates as well as increasing  values and decreasing b and Ks values, by which the phosphorus loss might be increased due to runoff or percolation [16,21]. Among others, the soil TP within 40-cm ridge width showed to be slightly increased after 35 DAP, indicated most effective in maintaining phosphorus content in soil. Rainfall B A Day after planting (DAP) Width of ridge (cm) Figure 6. Soil total-phosphorus within various dimensions of the horizontal ridges. Comparing the effects of three widths treated on nutrient availability (Fig. 6B), it was found that the 40-cm ridge width had highest capability to maintaining phosphorus content in soil, followed with the 50-cm (2.06 ton ha-1) and 30-cm ridge width (1.75 ton ha-1). This indicated that the 40-cm ridge width was most effective to entrapping rainfall and distributing water to deeper soil profile as well as to reduce runoff among others. Besides, the former ridge width had higher the , b, and Ks values, to which these capability were corresponded [22,23]. 4. Conclusion Dynamics of soil physical (, b, and Ks) and chemical (TN and TP) properties within various horizontal ridge dimensions and organic fertilizer applied potato land have been clearly identified. Over a cultivation period, the  tended to increase with optimum value of 0.44 cm3 cm-3 and the b tended to decrease with optimum values of 0.69 g cm-3, while the Ks was shown to be fluctuated with optimum valued of 0.024 cm s-1, regardless ridge dimensions. At the same period, there was tendency for TN and TP to decrease with optimum values of 3.94 and 2.14 ton ha-1, respectively, regardless ridge dimensions. Concerning with the ridge dimensions, the 40-cm ridge width was most effective in maintaining both physical (, b, and Ks) and chemical (TN and TP) properties of soil with optimum values of 0.41 cm3 cm-3, 0.71 g cm-3, 0.025 cm s-1, and 4.11 and 2.21 ton ha-1, respectively. In general, therefore, the 40cm ridge width was considerably suitable for the sustainable potato cultivation in tropical highland. 6 ICLAS-SURE IOP Conf. Series: Earth and Environmental Science 255 (2019) 012024 IOP Publishing doi:10.1088/1755-1315/255/1/012024 Acknowledgement This study was partly supported by the Directorate General for Higher Education of The Ministry of Research, Technology, and Higher Education (Kemenristekdikti) of Indonesia. The authors thank to Mr. Santoso for the help during field and laboratory data collection. References [1] Soleh, M., Arifin, Z., Pratomo, G., Santoso, P., and Nitiawirawan, I.G. 2002. 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