Benefits of organic residues and chemical fertilizer to productivity of rain-fed lowland rice and to soil nutrient balances

Abstract

Low yields and high risk characterize many rain-fed lowland rice environments, including those in Laos. Drought and fluctuating soil-water conditions (from aerobic to anaerobic states) can limit productivity and the efficient use of applied nutrients. Although addition of organic matter may improve the efficiency of fertilizer use, on-farm residues, for example farmyard manure (FYM), rice straw and rice hulls, are, currently, poorly utilized in these systems. Single and multi-year experiments were designed to evaluate the effect of these residues on rice productivity and efficiency of fertilizer use at four sites. Rice yield without fertilizer but with addition of residues ranged from 1.1 to 1.7 t ha -1 across sites and years. In response to fertilizer, yields increased on average by 1.4 t ha -1 . For all sites and years there was a significant response of yield to organic residues applied without fertilizer, with responses ranging from 0.2 to 1.4 t ha -1 . In 58% of cases there was no residue·fertilizer interaction (benefits of residues when applied with fertilizer were additive). In 38 and 4% of cases the interaction was negative (no response to residues if fertilizer was already applied) or positive (synergistic), respectively. In the multi-year studies, the type of interaction varied between years, suggesting that seasonal events, rather than soil type, determine the type of interaction. The greatest benefits of applying organic and chemical fertilizers together were observed in years when soil-water conditions were unfavorable (fluctuating anaerobic-aerobic conditions). The longterm effects of these different management strategies on soil nutrient balances suggest that N, P, and K balances were maintained as a result of balanced commercial fertilizer management but that addition of residues further enhanced these balances. All residues, when applied alone, resulted in positive soil Si balances; only with FYM were long-term N, P, and K balances maintained or positive, however. For resource-poor farmers, applying on-farm residues can be a sustainable approach to increasing productivity.

Assessing the Necessity of Surface‐Applied Preplant Nitrogen Fertilizer in Rice Systems

“…These authors reported that the NRE observed on‐farm were lower and ranged from 30 to 40%. Under rainfed rice conditions in Asia, Linquist et al (2007) reported NRE values of 13 to 30%. The higher on‐farm NRE values found in California relative to Asia, may reflect improved water and fertilizer management practices, a higher yield potential in a Mediterranean climate and the use of more physiological N use efficient rice varieties.…”

Micronutrients (Fe, Mn, Zn and Cu) balance under long-term application of fertilizer and manure in a tropical rice-rice system

“…Longterm manure application along with chemical fertilizers led to significantly higher values of soil available N compared to the other fertilization treatments. It has also been reported by many authors (Mann et al 2006;Linquist et al 2007;Shahid et al 2013) that the manure application leads to increase in soil available N and available P. However, higher levels of these soil nutrients were maintained when these nutrients were applied on long-term basis with the manure (Motavalli and Miles 2002). Unlike available N and available P, available K was the highest in NK + FYM treatment, followed by the NPK + FYM treatment, demonstrating the role of chemical fertilizers and organic manure in the supplementation of K in the soil.…”

Long-term application effects of chemical fertilizer and compost on soil carbon under intensive rice–rice cultivation

“…Soil organic matter is central to sustaining rice crop production and application of organic manures is considered to be an important strategy for the build-up of carbon stock in flooded soils (IRRI 1984;Linquist et al 2007). Under tropical conditions, the turn-over rate of soil organic matter can be rapid (Katayal et al 2001).…”