Poster presentation at the 4th International Rice Congress Authors: Iswandi Anas, Nindya Ayu Utari, Yolla Vivi Sukmasakti, and Rahayu Widyastuti Title: Ratooning with high yield Venue: Bangkok International Trade and Exhibition Centre (BITEC), Bangkok, Thailand Date: October 28-31, 2014

1. Rice Ratooning with High Yield is Possible!
ISWANDI Anas, Nindya Ayu UTARI, Yolla Vivi SUKMASAKTI and Rahayu WIDYASTUTI
Bogor Agricultural University (IPB), Campus IPB Darmaga, Bogor 16680, Indonesia
ABSTRACT
Ratooning is common practice for sugarcane in various countries. The yields of ratooned (regrown) sugarcane are somewhat lower than the first growth, but net profits are more, with input costs being less since there are no cost sfor seedlings, planting, and soil preparation. Ratooning is not interesting for rice since the yields of conventionally-grown ratooned rice are very low, the plants’ roots having degenerated under continuous-flooding conditions. This experiment evaluated the effects of alternative rice cultivation methods and the height for straw-cutting on the growth and yield of the first and second ratooned rice crop. Rice was grown under two crop management systems: (1) the System of Rice Intensification (SRI), and (2) conventional rice cultivation. The experiment was set up with randomized block design (RBD) and 5 replica- tions. Under SRI methods, 10-day-old single seedlings were transplanted at 25 cm x 25 cm distance and the soil was kept moist, not flooded. The conventional rice method used 25-day-old seedlings, 3 per hill, transplanted a distance of 20 cm x 20 cm under continuous–flooding conditions. Exactly the same doses of chemical fertilizers and organic fertilizer were applied for both methods. Eight days after harvesting the first rice crop, the straw was cut at a height of 3 or 15 cm from the soil surface; then the fields were flooded at 10 cm depth until shoots appeared. From the 4th week after harvesting, the soil of SRI plots was kept moist only while with the conventional cultivation methods, the soil was kept flooded. To maintain even plant growth, thinning of tillers or re-planting of tillers where necessary was done. Plant height, number of productive tillers, and yield were determined. Results showed that the vegetative growth of SRI rice cultivation was significantly better than with conventional rice cultivation, and the yield of SRI plots was significantly higher than conventional rice cultivation. Growth of the 1st and 2nd ratooned crop showed no significant differences in plant height between SRI and conventional ratooning, but the number of tillers of SRI ratooning was significantly higher. Shorter straw-cutting (at 3 cm) appeared better for both cultivation methods than longer straw-cutting (15 cm). The 1st growing season yield of SRI rice cultivation was 6.69 ton ha-1, while in con- ventional rice cultivation the yield was 5.23 ton ha-1. In the 1st ratoon, the yield from SRI rice cultivation with 3 cm straw cutting was 4.59 ton ha-1 , and with 15 cm straw-cutting it was 3.81 ton ha-1. With conventional rice cultivation with 3 cm straw-cutting, yield was 3.32 ton ha-1, and with 15 cm straw-cutting it was 2.80 ton ha-1 In the 2nd ratoon, the yield was not very high because no surrounding farmers were cultivating their fields and a lot of insects and birds attacked the rice. The yield of the 2nd ratoon was 0.74 tons ha-1 for SRI with straw-cutting of 3 cm; 0.70 ton ha-1 for SRI with 15 cm straw-cutting, 0.90 ton ha-1 for conventional rice cultivation with 3 cm straw-cutting and 0.63 ton ha-1 with 15 cm straw-cutting. Adoption of rice ratooning with SRI crop and water management will give reasonable benefits to rice farmers since good ratoon yields can be obtained with few additional inputs and little soil preparation cost, as these methods induce larger and better root growth as well as healthier plants that are more resistant to pests and diseases.
Keywords : Ratoon, SRI (System of Rice Intensification), Conventional Rice Cultivation, Length of Straw Cutting
INTRODUCTION
Ratooning, is common practice for sugarcane in various countries. A ratoon crop is the new cane which re-grows from the stubble of the previously-harvested crop. Although the yields of ratooned sugarcane are somewhat lower than from first growth, only up to 80%, the net profits were more because there are less input costs such as for seedlings and soil preparation (Sutardjo, 2002). Ratooning has not been interesting for rice cultivation since yields of ratooned rice are quite low, the plants’ roots having degenerated under continuous–flooding conditions. The adoption of SRI has been reported in many countries to increase rice yield and reduce inputs cost. Therefore farmers will get more benefits. It was reported by Erdiman (2013) that rice ratooning is becoming a common practice for rice cultivation by some farmers in West Su- matra. He reported that the length of straw-cutting, rice variety, fertilization, and soil moisture condition af- ter harvesting are the most important factors determining the success of rice ratooning. He reported ob- taining higher yields than those of the 1st growing season up to the 4rth ratooned planting. However, sci- entific reports on rice ratooning are still very few. The aim of this experiment was to evaluate the effect of the length of straw cutting on vegetative re-growth and the yield of the 1st and 2nd ratoonings with two rice cultivation managements, i.e., the System of Rice Intensification (SRI) and conventional rice cultivation.
MATERIALS AND METHODS
Rice was grown under two rice cultivation systems, namely the System of Rice Intensification (SRI) and conventional rice cultivation. The study was set up using randomized block design (RBD) with 5 repli- cations. In SRI, single 10-day old seedlings were transplanted at planting distance of 25 cm x 25 cm, and the soil was kept moist but not flooded. In conventional method, 25-day old seedlings, 3 seedlings per hill, were transplanted with a planting distance of 20 cm x 20 cm under continuous flooding . The size of the plots was 4 m x 5 m. Fertilization for both cultivation methods was the same: 250 kg urea ha-1, 200 kg SP- 36 ha-1 , and 100 kg KCl ha-1
Eight days after harvesting the first crop, the rice straw was cut at either 3 cm or 15 cm above the soil surface; then the soil was kept saturated for 2 weeks. At 4th week after harvesting, soil in SRI plots was kept moist while in conventional plots, the soils were kept flooded. To maintain even growth of rice ratooning, thinning of tillers or replanting of tillers was done as meeded. Fertilization was applied 2x, at 25 days and 40 days after first harvesting. The rate of fertilization was similar to the 1st growing season, i.e. urea was given 2x at a rate of 125 kg ha-1 for each fertilization, while SP-36 and KCl were given 100% at 25 days after 1st harvesting. Plant height, number of productive tillers, and grain yield were determined. Data were analyzed following analysis of variance (ANOVA) methods, using SAS for Windows software, according to Duncans’ Multiple Range Test (DMRT) (Gomez & Gomez, 1984).
RESULTS
FIRST GROWING SEASON
Figure 1. Performance of rice in 1st growing season cultivated under conventional and SRI methods. a) Sowing, b) at 46 DAS, c) at 70 DAS, d) at 95 DAS
THE FIRST RATOON
Figure 2. Performance of the 1st ratoon cultivated under conventional and SRI methods. a) Ratoon growth at 5 days after cutting (DAC), b) Ratoon growth at 60 DAC, c) Ratoon growth at 90 DAC.
Figure 4. The effect of straw cutting on crop yield in West Sumatra (Source: Erdiman, 2013)
REFERENCES
Erdiman. 2013. Teknologi salibu meningkatkan produktivitas lahan dan pendapatan petani. http:// sumbar.litbang.deptan.go.id/ind/images/pdf/padisalibu.pdf
Gomez KA and Gomez AA. 1984. Statistical Procedures for Agricultural Research (2nd edition). John Wiley & Sons, New York.
Sutardjo, E.R.M. 2002. Budidaya Tanaman Tebu. Bumi Aksara, Jakarta.
IRC14-0991
THE SECOND RATOON
Figure 3. Performance of 2nd ratoon cultivated under conventional and SRI methods. a) Ratoon growth at 5 days after cutting, b) Ratoon growth at 75 DAC, c) Ratoon growth at 75 DAC
Conventional
SRI
Conventional Method
SRI Method
Conventional Method
SRI Method
CONCLUSIONS
 The plant growth and yield at the 1st growing season under SRI cultivation methods was significantly higher compared to conventional cultivation methods.
 The yields of the 1st SRI ratoon at 3 and 15 cm straw cutting were 68.6% and 56.9%, respectively, of the yield of the 1st growing season, while the yields of the 1st conventional ratoon at 3 and 15 cm straw-cutting were 63.5% and 53.6%, respectively, compared with the 1st growing season. Shorter straw-cutting (@3 cm) gave better re-growth and better yield compared to longer straw-cutting (@15 cm).
 The measured yields of the 2nd ratoon crop for both cultivation methods and both straw-cutting heights were less than one ton-1 due to pest attacks from birds and insects, these having no other rice crops to feed on.
SRI
Conventional
Conventional
SRI
a
b
d
SRI
Conventional
c
b
SRI
SRI
SRI
Conventional
a
a
b
c
Conventional
c