M. I. U. Mollah
Rice Farming Systems Division, BRRI, Gazipur
Nur-e-Elahi
Rice Farming Systems Division, BRRI, Gazipur
A. Khatun
Rice Farming Systems Division, BRRI, Gazipur
M. M. Alam
Rice Farming Systems Division, BRRI, Gazipur
Intercropping, Pigeonpea [Cajanus cajan (L.) Millsp], Rice-Blackgram Crop Sequence
Upland experimental field of Bangladesh Rice Research Institute, Gazipur
Farming System
Pigeonpea, Rice, Black gram
The experiment was conducted at upland experimental field of Bangladesh Rice Research Institute, Gazipur in 1995 and 1996. Both row and mixed intercropping of pigeonpea in rice-blackgram crop sequence at 6:1 and 10:1 ratios along with their line sowing and broadcasting sole crops were tested. For 6:1 and 10:1 row ratios of rice and pigeonpea, one row of pigeonpea was added after 6 and 10 rows of rice, respectively, without sacrifice of rice rows. For mixed intercrops, the same amount of rice and pigeonpea seeds, used in row intercrops, were mixed before broadcast. The experiment was conducted in Randomized Complete Block Design with three replications. The unit plot size was 48m2. Modern upland rice variety BR21, blackgram variety BARImash-2 and a local variety of pigeonpea were used in this experiment. The seed rates for both sole and intercropped rice and blackgram were 80 and 30 kg ha-1, respectively. For pigeonpea sole crop, seed rate was 25 kg ha-1 and for intercrops, amounts of seed were measured on the basis of row number. Seeds of BR21 and pigeonpea were sown on 1st week of May in both the years following onset of monsoon. The distance between rice rows and sole pigeonpea were 20 cm and 75 respectively. The sole and intercropped rice were fertilized with 60-40-40-4kg ha-1 of N-P2O5-K2O-Zn and sole pigeonpea was fertilized with 20-40-40-4kg ha-1 of N-P2O5-K2O-Zn from urea, triple super phosphate (TSP), muriate of potash (MP) and ZnSO4, respectively. Whole amount of TSP, MP and ZnSO4 were applied one day before sowing at the time of final land preparation. Total urea for sole pigeonpea and one third urea for sole and intercropped rice were applied at basal and remaining urea was top dressed at 20 and 45 days after sowing (DAS). Each top dressing was followed by a hand weeding. No fertilizers were applied in blackgram.
The intercropped pigeonpea was clipped twice at 45 DAS of rice and 15 DAS of blackgram at 30 and 75 cm height, respectively. The pigeonpea biomass at each clipping was chopped and spread on the soil surface of the same plot. Recommended intercultural practices were followed for all the crops. Rice was harvested in the last week of August and blackgram was broadcast on the surface of untilled moist soil on same time in both the years. Blackgram and pigeonpea were harvested on first week of November and 2nd week of January, respectively, in both the years.
Grain and crop residue yields of all crops were measured at harvest. Blackgram residues were incorporated with soil. The rice equivalent yields (REY) were computed by converting yields of blackgram and pigeonpea into the yield of rice as follows:
The REY were analyzed statistically and means were compared by Duncan's New Multiple Range Test. A simple economic analysis of both sole and intercropping systems were done based on local market price of the products.
The competitive ratio (CR) and land equivalent ratio (LER) were computed using the formula as follows:
Where, CRa is the competitive ratio for crop ‘a’ in mixture with crop ‘b’ La and Lb are the relative yields of crop ‘a’ and ‘b’ respectively in the mixture and Za and Zb are their proportions.
Where, YA and YB are the intercrop grain yields of crop ‘a’ and crop ‘b’ and SA and SB are the corresponding sole crop grain yields. To compute CR and LER of the total system, grain yield of blackgram was converted to REY
Journal of Agronomy, 1: 34-37, 2002; ISSN 1680-8207
Journal