A global analysis of alternative tillage and crop establishment practices for economically and environmentally efficient rice production

Abstract

Alternative tillage and rice establishment options should aim at less water and labor to produce similar or improved yields compared with traditional puddled-transplanted rice cultivation. The relative performance of these practices in terms of yield, water input, and economics varies across rice-growing regions. A global meta and mixed model analysis was performed, using a dataset involving 323 on-station and 9 on-farm studies (a total of 3878 paired data), to evaluate the yield, water input, greenhouse gas emissions, and cost and net return with five major tillage/crop establishment options. Shifting from transplanting to direct-seeding was advantageous but the change from conventional to zero or reduced tillage reduced yields. Direct-seeded rice under wet tillage was the best alternative with yield advantages of 1.3-4.7% (p < 0.05) and higher net economic return of 13% (p < 0.05), accompanied by savings of water by 15% (p < 0.05) and a reduction in cost by 2.4-8.8%. Direct-seeding under zero tillage was another potential alternative with high savings in water input and cost of cultivation, with no yield penalty. The alternative practices reduced methane emissions but increased nitrous oxide emissions. Soil texture plays a key role in relative yield advantages, and therefore refinement of the practice to suit a specific agro-ecosystem is needed.

Figure 1

Rice grain yield comparison in five tillage/CE options with CT-TPR(wet). Meta-analysis and mixed model using (a,b) whole dataset (on-station plus on-farm) and (c,d) on-station dataset only. Error bars in meta-analysis indicate 95% confidence intervals, where difference in yield is considered significant if the 95% CI does not cover zero. In mixed model, * indicates significant yield difference at p < 0.05.

Figure 2

Comparison of rice grain yield in (a) conventional versus zero tillage irrespective of crop establishment (direct-seeding or transplanting) techniques, and in (b) direct-seeding versus transplanting irrespective of tillage (conventional, reduced, or zero) practices. Error bars indicate 95% confidence intervals; effect on yield is considered significant if the 95% CI does not cover zero.

Figure 3

Comparison of water input in rice under five tillage/CE options compared to CT-TPR. Error bars indicate 95% confidence intervals; effect is considered significant if the 95% CI does not cover zero.

Figure 4

Comparison of greenhouse gas emissions: (a) methane and (b) nitrous oxide from rice fields under five tillage/CE options versus CT-TPR(wet). Error bars indicate 95% confidence intervals; effect is considered significant if the 95% CI does not cover zero.

Figure 5

Cost of cultivation of rice under five tillage/CE options compared with CT-TPR(wet). Error bars indicate 95% confidence intervals; effect is considered significant if the 95% CI does not cover zero.

Figure 6

Net economic returns from rice under five tillage/CE options compared with CT-TPR(wet). Error bars indicate 95% confidence intervals; effect is considered significant if the 95% CI does not cover zero.