Internal efficiency, nutrient uptake, and the relation to field water resources in rainfed lowland rice of northeast Thailand

Abstract

Rice-based (Oryza sativa L.) rainfed lowlands are the major cropping system in northeast Thailand. Average yields are low, which is generally explained by frequent drought events, low soil fertility, and poor fertilizer response. However, neither the relative importance of these factors nor their interaction is well understood. Therefore, we analyzed an existing database on fertilizer trials conducted between 1995 and 1997 at eight different sites in northeast Thailand with the objective to determine indigenous nutrient supplies, internal efficiencies, and recovery efficiencies of applied nutrients in rainfed lowland rice. Of particular interest was the effect of variety type (traditional) and water supply on these components. Comparison of N, P, and K concentrations in grain and straw (average N-P-K grain concentration of 11.0-2.7-3.4 g kg -1 ; average N-P-K straw concentration of 5.2-0.9-16.4 g kg -1 ) in the traditional-type varieties used at all trial sites with literature values showed no differences for these parameters between traditional and modern-type varieties or between irrigated and rainfed environments. In contrast, internal efficiencies of N, P, and K (average IEN: 46 kg grain per kg N uptake; IEP: 218 kg grain per kg P uptake; IEK: 25 kg grain per kg K uptake) were much lower than reported for irrigated systems, and the difference was greatest for K, which is mainly accumulated in the straw. Indigenous nutrient supply (average INS: 38 kg ha -1 ; IPS: 10 kg ha -1 ; IKS: 89 kg ha -1 ) and recovery efficiency (average REN: 0.28 kg kg -1 ; REP: 0.13 kg kg -1 ; REK: 0.49 kg kg -1 ) were low but comparable to the lower values reported from irrigated systems. Average seasonal field water resources seemed to reduce the indigenous nutrient supply but had no or little effect on internal efficiency and recovery efficiency. We concluded that the main reason for the low system productivity without and with fertilizer in northeast Thailand is the dominant use of traditional-type varieties with low harvest indices, which was the dominant cause for the observed low internal nutrient efficiency. Therefore, intensification of rainfed systems through substantially increased nutrient inputs can be recommended only where varieties with an average

Field-specific potassium and phosphorus balances and fertilizer requirements for irrigated rice-based cropping systems

“…In both studies the rice yields were relatively low (<4 t ha −1 ). The higher RIE reported for traditional-type rice by Naklang et al (2006) than found for semi-dwarf modern rice such as in Witt et al (1999) and our study resulted from differences in harvest index rather than differences in tissue concentration of nutrients between the two types of rice.…”

“…Mukhopadhyay et al (2008), for example, in a fertilizer trial with rainfed rice in West Bengal in eastern India, reported mean harvest index=0.32 and mean accumulation of 33 kg K and 4.3 kg P per tonne of grain. In a multi-location trial in Thailand with 624 observations for traditional tall rice cultivars, Naklang et al (2006) reported median harvest index=0.28 and median plant accumulation of 48 kg K and 4.7 kg P per tonne of grain. In both studies the rice yields were relatively low (<4 t ha −1 ).…”

Assessing internal crop nitrogen use efficiency in high-yielding irrigated cotton

“…In China, Zhang et al (2008b) reported iNUE of 9.7 for upland cotton that yielded up to 1,000 kg/ha. In comparison, Naklang et al (2006) reported iNUE of 46 kg rice grain/kg crop N uptake.…”

Adaptation and performance of rice genotypes in tropical and subtropical environments

“…Observed yields of the indica, japonica, indica × japonica and indica × javanica genotypes in tropical (averages for the locations Ubon and Chiangmai) and cool subtropical (location Iwate) environments. ity due to poor soil structure, and low pH [45,46]. The influence of different soil characteristics on yield may be further explored using simulation models.…”