Studies on nitrogen cycling under different nitrogen inputs in integrated rice-fish culture in Bangladesh

Abstract

Management of nitrogen (N) in rice-fish culture is of great significance in order to exploit synergies between rice and fish. However, detailed and systematic studies on N cycling in rice-fish systems are rare. An experiment was carried out at the Bangladesh Agricultural University using the fish species common carp, Cyprinus carpio L., and Nile tilapia, Oreochromis niloticus (L.). Efficiencies of fertilizer and feed as N inputs were evaluated by establishing an apparent N balance. The different N input strategies for rice-fish (RF) treatments were:(1) with fish, with urea (101 kg N ha À1 , RF Urea), (2) with fish, with feed (22.6 kg N ha À1 , RF Feed I), and (3) with fish, with feed (41.5 kg N ha À1 , RF Feed I I ) . R i c e o n l y ( v a r . B R 2 8 ) w i t h u r e a (101.2 kg N ha À1 ) was added as the control (Rice only). Urea as N input (Rice only, RF Urea) resulted in negative apparent N balances (N output-N input), whereas N input in the form of feed (RF Feed I, RF Feed II) led to positive apparent N balances due to the lower N input. The presence of fish increased the grain and straw N output in RF Urea compared to Rice only, the effect being significant for straw (P < 0.05). Moreover, a significant difference in nitrogen uptake by rice was seen between the two feeding levels. The higher feeding rate in the RF Feed II treatment led to higher N outputs of grain, straw and fish compared to the RF Feed I treatment, a significant difference occurring for straw (P < 0.05). An apparent recovery efficiency of 48.7% was determined for the additional N input in RF Feed II compared to the RF Feed I teatment. An economic analysis revealed that the RF Urea treatment was the most profitable, as reflected by the highest gross margin. In conclusion, the results indicate that fish can improve nitrogen uptake by rice plants. Moreover, the supply of supplementary feed has a fertilizing effect on the rice due to the utilization of excreted feed nutrients by rice plants.

Nitrogen losses from integrated rice–duck and rice–fish ecosystems in southern China

“…Similar results have been reported in earlier studies (Wang 2000;Yang et al 2006;Oehme et al 2007). Table 5 also shows fish and duck yields (fresh weight) in paddy fields.…”

Nitrogen, sustainable agriculture and food security. A review

“…Good agricultural practice, where farmers aim at an ecologically and economically sustainable use of resources, should be the guiding principle in achieving sustainability goals. Furthermore, there are a range of technologies and practices that aim at resource conservation, such as: agroforestry, conservation agriculture, integrated aquaculture (fish-rice systems), integrated cropping management (ICM), integrated nutrient management (INM), integrated pest management (IPM) and water harvesting (Pretty, 2008;Hobbs et al, 2008;Gupta and Seth, 2007;Oehme et al, 2007;Tipraqsa et al, 2007;Yang H.S., 2006). Consequences of climate change for the occurrence of heat or drought stresses should also be taken into account (Olesen and Bindi, 2002).…”

Impact of phased harvesting on population structure, feed intake pattern and growth performance of Macrobrachium rosenbergii DeMan (giant freshwater prawn) in polyculture with carps in concurrent rice–fish culture

“…However, no distinct trend between the treatments was observed, and the sediment characteristics of the different treatments were indicative of a medium productive soil group (Banerjee 1967). When a rice field is stocked with fish, the nitrogen, phosphorous, and potassium (NPK) contents of the soil and water increases significantly (Oheme et al 2007). Fish movements in the rice field break the surface membrane formed by the microorganisms covering the soil, increasing the DO level in the soil and elevating its oxidation and reduction potential during the period of rice growth.…”