Different cropping patterns with principal crops of the selected regions were chosen and evaluated during July 2014 to December 2016 cropping seasons, to find out cropping pattern based water productivity and profitability in saline prone southern areas and drought prone northern areas of Bangladesh. The southern districts selected for conducting experiments were Barguna, Khulna and Satkhira, and the northern districts were Kushtia, Rajshahi and Rangpur.
All crops were grown in a following sequence starting with rabi crops as: Musatrd-Boro-T.Aman, Wheat-Mung-T.Aman, Potato-Mung-T.Aman and Chickpea-Mung-T.Aman. Cropping patterns for different regions were as follows:
Cropping patterns for Barguna:
1) Watermelon (cv.Big family) (Hybrid) - T.aus - T.aman (cv.BRRIdhan 53)
2) Tomato (cv.BARI Tomato 14) - T.aus - T.aman (cv.BRRIdhan 53)
Cropping patterns for Shatkhira:
1) Mustard (cv. BARI Sarisha 14) - Boro - T.aman (BINAdhan 7)
2) Wheat (cv. BARI Gom 25) - Mung - T.aman (BINAdhan 7)
Cropping patterns for Khulna:
1) Mustard (cv. BARI Sarisha 14) - Mung (cv. BARI Mung 6) - T.aman(BINAdhan 7)
2) Tomato (cv.BARI Tomato 14) - Jute (cv.072) - T.aman(BINAdhan 7)
Cropping patterns for Rajshahi:
1) Wheat (cv. BARI Gom 28) - Mung (cv. BARI Mung 6) - T.aus (BRRI dhan 55)
2) Chickpea (cv.BARI Chhola 4) - Mung (cv. BARI Mung 6) - T.aman (BRRI dhan 56)
Cropping patterns for Rangpur:
- Potato (cv. Diamant)- Maize (cv. BARI Hybrid Maize 9) - T.aman (cv.BRRIdhan 57)
- Tomato cv.BARI Tomato 14 -T.aus cv.BRRIdhan 48)-T.aman cv.BRRIdhan 57
Cropping pattern for Kushtia:
- Wheat (cv. BARI Gom 28) - Mung (cv. BARI Mung 6) - T.aman (BINAdhan 7)
- Wheat (cv. BARI Gom 28) - Sesame (cv. BARI Til 4) - T.aman (BINAdhan 7)
Crops were grown in the farmers' field of selected locations. Sowing/transplanting and harvesting time of different crops grown in different locations are listed in with their respective varieties.
Kharif 2 season (Aman season):
Field experiments with T.Aman rice were conducted in saline and drought prone areas to investigate supplemental irrigation effects on the yield of T.Aman rice under changing climate situation. Some promising varieties like BRRI dhan 53, 56, 57 were used as test crop for Barguna, Rajshahi and Rangpur regions and another promising variety 'BINAdhan 7' was used for Satkhira, Khulna and Kushtia regions.
Based on the scarce availability of water and analysis of previous rainfall patterns in aman season, four treatments were selected for the studies. These were:
T1: rainfed (no supplemental irrigation and treated as farmers' practice),
T2= one supplemental irrigation at booting stage,
T3= one supplemental irrigation at grain filling stage,
T4 = two supplemental irrigations at booting and grain filling stages
In all the cropping patterns, T.aman rice was transplanted between July 15-30, 2014 with seedlings of the selected rice cultivars when the seedlings were 35-40 days old. The experiments were laid out in randomized complete block design and the treatments were replicated thrice. Recommended fertilizer dose of urea, TSP and MP were applied at the time of final land preparation except urea, half of which was applied as top dressing. Plant spacing was 30 cm in rows of 20 cm apart. Plot size was 5 m x 4 m. Irrigation was applied as per treatment with 5 cm standing water depth. Other cultural practices were also done as and when necessary. Different growth and agronomic parameters were collected at different growth stages. Rest of the agronomic data was collected during harvest. Crops were harvested between 01-15 November 2014.
Rabi season:
After T. Aman harvest the rabi experiments were started during October-November 2014 period at the project sites. The selected crops for this were potato, wheat, mustard and tomato. The experiments were laid out in randomized complete block design with the treatments replicated thrice.
Potato:
The whole potato tubers (cv. Diamant) were planted on 19/11/2014 as a part of the cropping pattern T.aman-potato-maize in Pirgonj, Rangpur. The treatments were as follows:
T1 = Farmers' practice,
T2= Irrigation at stolonization and tuberization stages
T3= Irrigation at stolonization and bulking stages
T4 = Irrigation at stolonization, tuberization, and bulking stages
Tomato:
In the cropping pattern T.aman-tomato-jute in Dumuria, Khulna and T.aman-tomato-T.aus in Barguna, tomato seedlings of 30-35 days old were transplanted after harvesting of T.aman rice. The treatments for tomato were as follows:
T1= Farmers' practice (control)
T2= Drip irrigation at 3 days interval
T3= Alternate furrow irrigation at 10 days interval
T4= Furrow irrigation at 10 days interval
Wheat:
Wheat were sown during 15-30 November at a row spacing of 20 cm in the cropping pattern Wheat-Mung-T.aman and Wheat-Sesame-T.aman in Kushtia region, in Wheat-Mung-T.aman pattern in Satkhira and Wheat-Mung-T.aus pattern in Rajshahi. Treatments set up for this crop were as follows:
T1= Farmers' practice
T2= One irrigation at CRI (17-21 DAS) stage
T3= Tow irrigations at CRI and maximum tillering (40-45 DAS) stages
T4= Three irrigations at CRI, maximum tillering and flowering (70-75 DAS) stages
Mustard:
Mustard were sown in rows at 30 cm spacing in the farmers field of Satkhira and Khulna in Mustard-Boro-T.aman and Mustard -Mung - T.aman cropping pattern respectively. Irrigation practices for this crop were as follows:
T1= Farmers' practice (control)
T2= One irrigation at pre-flowering stage
T3= One irrigation at pod formation stage
T4= Two irrigation at pre-flowering and pod formation stages
Chickpea:
Chickpea was sown in farmers' field of Godagari, Rajshahi within 2-3 days of T.aman harvesting in order to utilize profile soil moisture for its germination and growth. Irrigation treatments applied for this crop were as follows:
T1= Farmers' practices
T3= One at early vegetative stage (20-25 DAE)
T4= One irrigation at pre-flowering stage (60-65 DAE)
Irrigation water was applied up to the field capacity as per treatment. Soil sampling for monitoring moisture content in the experiment fields were done up to 60 cm depth at an internal of 20 cm. Moisture contents were determined gravimetrically. Moisture content at sowing and harvest were determined. Other cultural practices were also done as and when necessary. Different growth and agronomic parameters were collected at different growth stages. Rests of the agronomic data were collected during harvest. All weather data of the cropping period influencing crop water use were also collected. Total water used by the crop was determined using water balance equation. Water productivity for the different treatments were predicted in Kg m-3 as the ratio of yield and total water used by the crop.
Watermelon:
T1= Farmers' practice
T2= Drip irrigation at 3 days interval with mulch
T3= Ring basin irrigation at 10 days interval with mulch
T4= Ring basin irrigation at 15 days interval with mulch
Kharif I season:
Kharif I experiments were started after harvesting of rabi crops during March-April 2014 period at the project sites. The selected crops for this season were T.aus, maize, mung, sesame, jute and watermelon. The experiments were laid out in randomized complete block design and replicated thrice.
T.Aus:
Like T.aman, similar experiments on T.Aus rice were conducted in Watermelon-T.aus-T.aman, Tomato-T.aus-T.aman and Wheat-Mung-T.aus cropping sequences to investigate supplemental irrigation effects on the yield of T.Aus rice under changing climate situation. A promising rice variety like BRRI dhan 48 was used as test crop for Barguna and Rangpur regions and another promising variety 'BRRI dhan 55' was used for Rajshahi regions.
Treatment set up for T.aus was same as the treatments for T.aman. These were:
T1=rainfed (no supplemental irrigation and treated as farmers' practice),
T2=one supplemental irrigation at booting stage,
T3=one supplemental irrigation at grain filling stage,
T4=two supplemental irrigations at booting and grain filling stages
Maize:
T1= Farmers' practice
T2= Irrigation applied at silking stage
T3= Irrigation applied at grain filling stage
T4= Irrigation applied at silking and grain filling stages
Mungbean:
T1= Farmers' practice
T3= Irrigation at vegetative stage (20-25 DAE)
T4= Irrigation at flowering stage (40-45 DAE)T5= Irrigation at vegetative and flowering stages
Jute:
Effect of supplemental irrigation on jute was studied in Tomato - Jute - T.Aman cropping sequence in the farmers' field of Dumuria, Khulna. Sowing of jute seed (cv. JRO 072) was done on 1st week of April 2014 at row spacing of 15 cm. Randomized complete block design was used with three replications having a plot size of 6 m x 5 m. Irrigation treatments tried for jute were:
T1= Farmer’s practice (pre-sowing irrigation-PI)
T2= PI + one supplemental irrigation at seedling stage (15 DAE)
T3= PI + one supplemental irrigation at early vegetative stage (30-35 DAE)
T4= PI + two supplemental irrigations at seedling and early vegetative stages
Recommended fertilizer doses were used. Intercultural operations like thinning and weeding were done before second irrigation. Except irrigation, all other agronomic practices remained the same for all treatments. Crop was harvested during the second week of August 2014.
Sesame:
Sesame was sown in a cropping sequence wheat-sesame-T.aman in Kushtia on 08 April 2014 at a spacing of 30 cm x 5 cm. Unit plot size was 5 m x 4 m. The experiment was conducted in farmers' field in randomized complete block design with three replications. Four irrigation treatments were tried.
T1= Farmer’s practice
T2= One supplemental irrigation at vegetative stage (20-25 DAE)
T3= One supplemental irrigation at flowering stage (40-45 DAE)
T4= Two supplemental irrigations at vegetative and flowering stages
Fertilizer application rate was 115-140-45-105-5-10 kg/ha of urea, TSP, MOP, gypsum, zinc sulphate, boric acid, respectively. All intercultural operations were done timely. Insecticide (Ripcord) was sprayed to control pod borer. Irrigation was applied as per schedule. A pre-sowing irrigation was applied to ensure the seed germination. At maturity, crop was harvested on 26 June 2014 and all agronomic data were collected at harvest.