In order to compare the yield between maximum attainable yield and farm-level yield, apart from research data, information were also collected from two selected major rice growing areas. The rice growing areas included Muktagacha Upazila of Mymensingh and Nokla Upazila of Sherpur district. A total of 18 research plots were set up at farmers’ field in order to assess the achievable yield of the selected aman rice varieties. The selected aman varieties are Bina dhan 7, BR-11, BRRI dhan40, BRRI dhan41 were set up at farmers’ field in order to assess the achievable yield of aman rice varieties. The research plots were jointly conducted, monitored and supervised by the concerned farmers, SAAOs from DAE and researchers. Production inputs like seeds, fertilizers, pesticides etc. were provided in advance from the project. In order to compare the yield between the research plots and farmers’ actual yield, field data were collected from the aman rice growers of the selected Upazilas. Random sampling procedures were used for determining the proportionate samples from the population. Data were collected from the two consecutive years 2011 and 2012. For validation of information on different causes of yield gaps, 4 Focus Group Discussions (FGDs) were conducted with the farmers. In addition, in order to make the findings more authentic 20 Key Informants Interviews (KIIs) were conducted personally by the researchers with the extension personnel, input dealers, and development workers. Apart from this 4 Field Days (FDs) were also conducted.
Measurement of yield gap Yield gap of a variety was measured on the basis of the difference between the achievable yield (kg/ha) of research plot yield and a farmer’s actual yield (kg/ha) obtained at the farmers’ plot and then compared it to the percentage of achievable yield. Thus, the yield gap of a variety could vary from 0 to 100%.
Determining the practice gap in aman rice cultivation Seed rate, seed quality, seedling age, application of urea, TSP, MoP and gypsum are considered to be yield determining factors. Practice gap for each yield determining factor however was measured on the basis of difference between recommendation and actual application. The formula used in this regard was as follows: Deviation proportion G = R-A /R
Where, G= gap R= Recommended practices for the variety A= Actual practices done for the same variety by the respondents at research station
Constraints in aman rice cultivation leading to yield gap The respondents were asked to indicate the extent of their constraints during the cultivation of Bina dhan 7, BR-11, BRRI dhan 40, BRRI dhan 41 in a four point rating scale - high, medium, low and not all with the weightage of 3, 2, 1 and 0 respectively. The constraints facing index (CFI) was computed by using the following formula: CFI = Ph X3 + Pm X 2 + Pl X 1 + Pn X0
where, Ph = Number of farmers facing the constraint as high Pm = Number of farmers facing the constraint as medium Pl = Number of farmers facing the constraint as low Pn = Number of farmers facing the constraint as not at all