Dynamics in soil respiration in safflower (Carthamus tinctorius L.) based cropping systems with and without addition of organic manures.

Abstract

A field experiment was conducted at Hyderabad from 2005-06 to 2007-08 during rainy and post-rainy seasons on Vertisols to develop sustainable nutrient management practice/s for increased productivity of safflower (Carthamus tinctorius) based cropping systems (greengram-safflower, soybean-safflower, maize-safflower) under rain fed conditions. The highest values of soil respiration were observed at flowering stage of rainy season crops. During the rainy season, maize-safflower cropping system recorded the highest level of soil respiration (335 Ilg C/g soil/IO d). No significant differences were observed between soybean-safflower (304 Ilg C/g soillJ 0 d) and greengram-safflower (294 Ilg C/g soilll 0 d). The highest values of soil respiration were observed at vegetative stage Glyricidia and FYM were applied in first week of June and incorporated in to the soil. Inorganic fertilizer was applied just before sowing of the crops. Crops were sown with the onset of monsoon on broad bed and furrows (BBF) of 1.2 m broadbeds with a furrow of 0.3 m with animal drawn implement. Four rows of greengram and soybean (30 cm x 10 cm) and two rows of maize (75 cm x 30 cm) were sown on each BBF. Three rows of safflower (45 cm x 20 cm) were sown on each BBF. Rainy season crops were sown with the onset of monsoon. The recommended fertilizer of greengram, soybean, maize and safflower was 20-40-20, 20-60-20, 120-50-40 and 40-25-25 N-P20s-K20, respectively. The inorganic fertilizer was supplied in the form of urea, single super phosphate and muriate of potash. Crops were protected through the recommended pesticides as and when required. Soil samples (0-20 cm depth) were collected at different stages of crop growth with core sampler. The samples were stored under refrigerated condition. Microbial biomass-C (MBC) and -N (MBN) were estimated by using chloroform fumigation incubation method as described in Horwath and Paul (1994). Statistical analysis of the data was carried out using standard analysis of the variance.