Abstract: Four field experiments were conducted under different Agro-ecological zones (AEZs) of Bangladesh at Ishurdi (AEZ 11), Jamalpur (AEZ 9), Rajshahi (AEZ 11) and Thakurgaon (AEZ 1) in 2001-2002 cropping season. The main aims of the studies were to determine the fertilizer requirements on productivity of cane and intercrops (potato and onion) and their economics under sugarcane based cropping systems. Cane yield was enhanced when it was intercropped with potato and onion for the residual effect of applied fertilizer to intercrops. Net economic return was greater in cane intercropped with potato and onion over sole crop for all the experiments. Intercropping potato with sugarcane using FRG’97 rates of fertilizer for cane (130 kg N, 35 kg P, 60 kg K, 20 kg S and 3 kg Zn ha-1) and potato (50 kg N, 10 kg P and 20 kg K ha-1) gave higher economic benefit at Ishurdi site. In Jamalpur site, sugarcane intercropped with potato following fertilizer rates based on BSRI’98 for cane (150 kg N, 42 kg P, 100 kg K, 30 kg S and 2 kg Zn ha-1) and potato (50 kg N, 10 kg P and 40 kg K ha-1) gave the highest net profit. But, the treatment received fertilizers as per FRG’97 showed higher economic benefit from sugarcane-onion intercropping systems both at Rajshahi and Thakurgaon sites.
INTRODUCTION
Usually sugarcane is planted in widely spaced (1.0 m) rows in Bangladesh. Sugarcane plants have large lateral spread when fully-grown but initial rate of increase in horizontal spread is slow. Plant sugarcane canopy does not close until 3.5-5.0 months, depending mainly on variety and growing period. During this period, the inter-row space remains unoccupied and the young cane does not make much demand on growth resources, especially light and water, available in the inter-rows. Hence there is an ample scope to grow fast-growing intercrops in the vacant space between the cane rows. Sugarcane intercropping helps increasing both the yields of intercrops and cane. This is due to the complementary effects of different short duration crops and sugarcane which is an added advantage over sole cane that was reported by several workers (Imam et al., 1990 and Bokhtiar et al., 1995). The sugarcane crop depletes a considerable amount of nutrients from soil. As a consequence, soils are loosing its inherent ability to supply nutrients for sustainable production. Yadav et al. (1987) reported that the organic matter content of sugarcane soil increased due to companion cropping of pulses. The combined return of cane and potato was always higher when both the crops were planted together and received their full rates of fertilizer (Bokhtiar et al., 2002). Yield potentiality and nutrient requirement of cane and intercrops under sugarcane based intercropping systems varied from place to place due to prevailing climatic conditions and edaphic factors. Hence a study has been made to determine the fertilizer requirement of sugarcane as well as intercrops potato and onion at different Agro-ecological zones (AEZs) of Bangladesh.
MATERIALS AND METHODS
Four field experiments were conducted in 2001-2002 cropping season in different AEZs at Ishurdi, Jamalpur, Rajshahi and Thakurgaon sites of Bangladesh. Experiments were laid out in randomized complete block design with four replications. The unit plot size was 8x6m. The tested varieties of sugarcane were Isd 20, Isd 28 and Isd 29. Cardinal and Taherpuri variety were used as tested material for potato and onion, respectively. All the recommended cultural management practices were followed for sugarcane and intercrops when required. Full amount of TSP, gypsum, zinc sulphate, one third of urea and MP were applied as basal in the trenches and mixed thoroughly with soil. Rest amount of urea and MP were top dressed in two equal splits at 120 day after plantation (DAP) and at 180 DAP i.e. at tiller completion stage. For intercrops, half of urea and MP, full amounts of TSP and gypsum were applied as basal doses. Remaining half of urea and MP were top-dressed after 45 DAP. Sunhemp as green manure crop was raised and incorporated in situ after 40±5 days of seed sowing. The incorporated green manure contained 1.65% N. Necessary data were recorded and analyzed using the least significant differences test (LSD) at P=0.05. Sugarcane crop was harvested 13 months after planting.
The treatments deployed are as follows:
For sugarcane-potato intercropping systems
| T1 | - | Recommended fertilizer dose for sole sugarcane following FRG’97 for MYG |
| T2 | - | Fertilizer dose for sole sugarcane based on soil test value for HYG |
| T3 | - | Fertilizer dose for sole cane as per BSRI recommendation’ 98 for HYG |
| T4 | - | Fertilizer dose for sugarcane + potato following FRG’97 |
| T5 | - | Fertilizer dose for sugarcane + potato following BSRI recommendation’ 98 |
| T6 | - | Fertilizer dose for sugarcane + potato following BSRI’98+ Sunhemp |
For sugarcane-onion intercropping systems: This experiment also comprised of six treatments and received fertilizer similar to sugarcane-potato only the difference is intercrop, onion.
FRG’97-Fertilizer Recommendation Guide’1997; BSRI’98-Bangladesh Sugarcane Research Institute’1998; MYG-Moderate Yield Goal (80±10 t ha-1): HYG- High Yield Goal (100±10 t ha-1)
RESULTS AND DISCUSSION
Yield attributes and yield: At Ishurdi site, significantly lowest number of tillers (200.36x103 ha-1), millable cane stalks (129.53x103 ha-1) and yield (90.93 t ha-1) of cane were obtained from the T1 treatment while the highest number of tillers (247.65x103 ha-1), millable cane stalks (149.06x103 ha-1) and yield (121.14 t ha-1) were obtained from T5 treatment combination which received BSRI’ 98 fertilizer rates both for cane and potato (Table 1). Results of the study also indicated that raising of intercrops influenced cane yield significantly. Application of recommended fertilizers for cane and potato produced higher yields of 126.4, 121.14 and 118.90 t ha-1 in T4, T5 and T6, respectively. This might be due to complementary effects of growing intercrops and residual effects of plant nutrients on sugarcane crop that ultimately enhanced more cane yield compared to sole cane.
At Jamalpur site, data on tillers, millable cane stalks and yield of potato significantly varied due to different fertilizer management practices. The increase of cane yield was 7.3 and 5.2% in T5 and T6 with intercrops over sole cane (T1). The results indicate that cultivation of the intercrop with sugarcane caused no adverse effects on cane yield rather significantly increased its yield compared to sole cane. It is presumed that residual effect of applied fertilizers as well as additional cultural management for the intercrop resulted more yields. At both the locations, maximum potato yield of 6.41 and 6.38 t ha-1 as intercrop was found in T6 treatment received fertilizers based on BSRI’98 at Ishurdi and Jamalpur, respectively.
At Rajshahi, the highest number of tillers of 176.87x103 ha-1 was produced in T4 treatment followed by T5 treatment while the lowest number of tillers (148.95x103 ha-1) was produced in T1 treatment. The highest number of millable cane stalks (136.81x103 ha-1) and the highest cane yield of 114.79 t ha-1 were obtained from T6 treatment that received fertilizer based on BSRI’98 followed with sunhemp (Table 2).
At Thakurgaon there was insignificant differences were observed in respect of tillers, millable cane stalks and cane yield among the treatments but an increasing trend was observed. The highest cane yield of 72.44 t ha-1 was found in T4 treatment received with the fertilizer following FRG’97 which was closely followed by T5 and T6 treatments. For both the locations the yield increase was noticed in those treatments where, onion raised as companion crop. It is assumed that residual effect of applied fertilizers as well as additional cultural management for intercrop, i.e. beneficial association of intercropping with sugarcane, resulted to more yields. Brix per cent was significantly different among the treatments and it was the highest (18.80%) in T6. The maximum yield of intercrop onion was obtained 7.81 in T5 at Rajshahi and 4.42 t ha-1 in T6 at Thakurgaon, respectively.
Economics of fertilizer use: The economic analyses of different fertilizer packages were done considering the total variable cost and return for all the treatments (Table 3 and 4). At different sites the highest net benefit and BCR was varied, as it was associated with the yield production as well as fertilizer requirement of the treatments. In sugarcane-potato intercropping systems at Ishurdi the highest BCR of 3.54 was obtained in T4 treatment followed by 3.50 in T5 treatment. At Jamalpur all though the highest BCR of 3.32 was found in T2 treatment but the treatment T5 gave the highest net profit with BCR 3.20. In case of sugarcane-onion intercropping systems, at Rajshahi the highest BCR of 4.14 was obtained in T4 which was closely associated with BCR of 4.02 in T5.
| Table 1: | Yield and yield contributing parameters of sugarcane as affected by different fertilizer management packages at Ishurdi and Jamalpur sites |
| Table 2: | Yield and yield contributing parameters of sugarcane as affected by different fertilizer management packages at Rajshahi and Thakurgaon sites |
| In a column the figures having similar letter do not differ significantly as per LSD at 5% level | |
| Table 3: | Economic analysis of different fertilizer management under sugarcane based intercropping systems at Ishurdi and Jamalpur site |
| Table 4: | Economic analysis of different fertilizer management under sugarcane based intercropping systems at Rajshahi and Thakurgaon site |
| Fertilizer cost (Tk. kg-1) ; Urea = 6.50 ; TSP =14.00 ; MP =9.50 ; Gypsum =4.00 ; Zinc sulphate = 60.00 ; MgO =40.00 ; FYM = 0.40; Sugarcane =1150 Tk t-1 ; Labor = Tk 70 person-1day-1 Intercrop (Tk.kg-1) ; Potato = 6.00 and Onion 10.00 | |
| Table 5: | Initial and post harvest soil status under different fertilizer management at Ishurdi and Jamalpur site |
| Table 6: | Initial and post harvest soil status under different fertilizer management at Rajshahi and Thakurgaon site |
At Thakurgaon the highest BCR of 2.38 was also found in T4 treatment that was followed by BCR of 2.18 in T6.
Soil fertility status: The initial and post harvest soil nutrient status of soil pH, organic carbon, total N, available P, K and S for all the sites are presented in Table 5 and 6. There were considerable decreases in organic matter in soils. A little change was observed on soil pH at all sites. The changes in total N, available P, K and S were not conspicuous due to a single year practice of using different fertilizer doses in the experimental plots under study.
It is concluded that intercropping potato with sugarcane using FRG’97 rates of fertilizer for cane and potato gave higher economic benefit at Ishurdi site. Sugarcane intercropped with potato following BSRI’98 rates of fertilizer for cane and potato gave higher net profit at Jamalpur site. Application of fertilizers as per FRG’97 showed higher economic benefit from sugarcane-onion intercropping systems both at Rajshahi and Thakurgaon sites.