Effect of management practice and cropping intensity on nutritional status of low ganges river floodplain soils

Abstract

Field experiments were conducted at the farmers’ field of Lower Ganges River Floodplain (AEZ12) in Kashiani upazila of Gopalganj District during the period of 2013-2015 with an objective to find out the effect of crop production on the nutritional status of soils as well as the nutrient balances due to the nutrient management. Two cropping patterns i.e. Jute - T. aman – Mustard in Sara series and Jute - T. aman - Lentil in Gopalpur series were practiced to maintain croppingintensity. The field experiments were laid out in randomized complete block design (RCBD) having eleven treatments composed of chemical fertilizers alone or in combination with cow dung, poultry manure and oilcake with three replications. Each plot size was 5m x 4m. The integrated use of chemical fertilizers and manures resulted considerable improvement of the physical and chemical properties of soils. The treatments had significant effect on bulk density and total porosity in Gopalpur series soil. The lowest bulk densities of 1.17 and 1.20 g cm-3 were recorded with 75% of fertilizers applied by farmers + 75% recommended S&B + cow dung treatment in soils of Sara and Gopalpur series, respectively. The hydraulic conductivity and soil moisture content were also significantly higher with 75% of recommended fertilizer + cow dung treated plots in soils of both Sara and Gopalpur series. The significantly higher organic matter content of 1.71% and CEC of 28.13cmol kg-1 soil were obtained with 75% of recommended fertilizers + cow dung treatment in both soil series. But, the 75% of recommended fertilizers + oilcake treatmentprovided significantly maximum total N contents of 0.123 and 0.148% and available S contents of 35.04 and 41.70 µg g-1in Sara and Gopalpur series, respectively. The application of 75% of farmers’ practice + 75% of recommended S&B+ poultry manure and 75% of recommended fertilizers + cow dungtreatmentsincreased the available P and K contents to the highest level. The soil analysis based treatment produced significantly higher available Zn content (1.183 µg g-1) in Sara series. With some exceptions, the changes in available Na, Ca, Mg, Fe, Mn, B and Cu contents in both soils were found non-significant due to the application of different treatments. The results revealed that the combined application of chemical fertilizers and manures resulted in remarkable improvement in soil properties by increasing organic matter and nutrient contents in both calcareous soils. The soils of sixteen different locations showed considerable variations in nutrient contents and arefree from heavy metal contaminations. The significantly higher yields of jute fibre of 4.98 t ha-1,jute stick with barkof 14.55 t ha-1, rice grain of 4.57 t ha-1, rice straw of 6.22 t ha-1, mustard grain of 1.45 t ha-1 and stover of 4.52 t ha-1in Sara series, and yields of jute fibre of 5.01 t ha-1, jute stick with barkof 14.38 t ha-1 and rice grain of 4.54 t ha-1in soils of Gopalpur series were found with 75% of recommended fertilizers + oilcake treatment. While the 75% of recommended fertilizers +poultry manure treatment provided significantly higher yields of rice straw of 4.52 t ha-1, lentil grain of 1.74 t ha-1 and lentil stover of 1.73 t ha-1 in soils of Gopalpur series. The nutrient contents and uptake were significantly higher with the application of 75% of recommended fertilizers + oilcake in Sara and Gopalpur series, which were followed by 75% of recommended fertilizers+poultry manure treatment and then 75% of recommended fertilizers+cow dung treatment. With a few exceptions, the treatment consists of75% of recommended fertilizers + oilcake resulted in considerable higher nutrient contentsand uptake in the examined crops among the three manures based treatments.The results shows that the chemical fertilizers+oilcaketreatment was more suitablethan the other treatments to supply sufficient nutrients for the crops under Jute - T. aman - Mustard and Jute - T. aman - Lentil cropping patterns. Thus, the apparent balances for N, P, S, Zn and B were found positive in case of combined application of chemical fertilizers and organic manures (cow dung, poultry manure and oilcake) except K balance, while only chemical fertilizers based treatments and control showed negative balances. The above results revealed that the nutrient management through theapplication of 75% of recommended fertilizers +oilcaketreatment resulted the higher nutritional status and maintained nutrient balancesof soils in AEZ 12 than that of chemical fertilizers alone (fertilizers applied by farmers or recommended fertilizers by BARC or soil test based treatment) or in combination with cow dung and poultry manure treatments. The application of 75% of recommended fertilizers +2 t ha-1oilcakecould be recommended forthe introduced cropping patterns i.e. Jute - T. aman - Mustard and Jute - T. aman - Lentil instead of two crops based cropping patterns in AEZ 12 for sustainable higher yield in highland and medium highland soils of Sara and Gopalpur series, respectively.