Performance of summer crops in rice fallows and its effect on succeeding transplanted rice

Abstract

A field experiment entitled “Performance of summer crops in rice fallows and its effect on succeeding transplanted rice” was taken up at the Cropping systems research station, Karamana, Thiruvananthapuram during February 2008 to October 2008 that covered the summer (third crop) and virippu (the first crop) seasons of rice cultivation. The main objectives of the experiment was study the performance of different upland crops in the summer rice fallows of southern Kerala in terms of resource utilisation, yield, soil health and carry over effect on succeeding rice crop, and to arrive at a sound practice of summer rice fallow utilization. The experiment was laid out in a randomised block design with three replication and seven treatments (T1 - Control or summer rice fallow, T2 - Sweet potato, T3 - Pumpkin, T4 - Sesamum, T5 - Amaranthus, T6 – Cowpea and T7 - Daincha) which were followed by rice crop in the virippu season. Al the crops were raised as par the KAU package of practices recommendations.

Results of the study revealed that there was a significant variation in the composition of weed flora of summer crops and the succeeding rice crop. The associated weed species of summer crop also varied significantly. Cowpea (T6) being grown on pandal had no weed separation effect and hence had the higher WDMP and SDR. Amaranthus (T5) recorded the highest economic yield and rice yield equivalent, water productivity, net profit and B:C ratio. However, sweet potato (T2) recorded the highest energy yield per unit area and highest nutrient uptake of macro and micro nutrients. The nutrient balance sheet showed a general negative balance for N and P except for sweet potato (T2) and Daincha (T7) where as K showed a negative balance for all treatments. The succeeding rice crop was not significantly influenced by the summer crops with respect to yield and yield attributes. The post rice soil was left less acidic by pumpkin-rice sequence, where as Daincha-rice significantly increased the soil acidity. The post rice soil significantly varied in the available P and K with the highest value noted in Amaranthus-rice (T5). Significantly higher quantity of Zn was recorded in Daincha-rice (T7).