Natural farming improves crop yield in SE India when compared to conventional or organic systems by enhancing soil quality

Abstract

Zero Budget Natural Farming (ZBNF) is a grassroot agrarian movement and a state backed extension in Andhra Pradesh, and has been claimed to potentially meet the twin goals of global food security and environmental conservation. However, there is a lack of statistically evaluated data to support assertions of yield benefits of ZBNF compared to organic or conventional alternatives, or to mechanistically account for them. In order to fill this gap, controlled field experiments were established in twenty-eight farms across six districts, spanning over 800 km, over three cropping seasons. In these experiments, we compared ZBNF (no synthetic pesticides or fertilisers, home-made inputs comprising desi cow dung and urine with mulch) to conventional (synthetic fertilisers and pesticides) and organic (no synthetic pesticides or fertilisers, no mulch, purchased organic inputs, e.g. farmyard manure and vermicompost) treatments, all with no tillage. Comparisons were made in terms of yield, soil pH, temperature, moisture content, nutrient content and earthworm abundance. Our data shows that yield was significantly higher in the ZBNF treatment (z score = 0.58 ± 0.08), than the organic (z= -0.34 ± 0.06) or conventional (-0.24 ± 0.07) treatment when all farm experiments were analysed together. However, the efficacy of the ZBNF treatment was context specific and varied according to district and the crop in question. The ZBNF yield benefit is likely attributed to mulching, generating a cooler soil, with a higher moisture content and a larger earthworm population. There were no significant differences between ZBNF and the conventional treatment in the majority of nutrients. This is a particularly important observation, as intensive use of synthetic pesticides and fertilisers comes with a number of associated risks to farmers' finances, human health, greenhouse gas emissions, biodiversity loss and environmental pollution. However, long-term field and landscape scale trials are needed to corroborate these initial observations.

Supplementary information: The online version contains supplementary material available at 10.1007/s13593-023-00884-x.

Keywords: Conventional agriculture; Organic farming; ZBNF; Zero budget natural farming.

Fig. 1

Two example field experiments comparing Zero Budget Natural Farming (ZBNF) to conventional and organic alternatives. a Before sowing (mulch on ZBNF treatment plots). b with crops established (yellow sticky traps on ZBNF treatment plots). Photo credit: a Ramyasree Reddymalli (RySS, Prakasam District) and b Lakshmi Bhairava Kumar (RySS, Anantapur District).

Fig. 2

Effect of farming practice on yield (z transformed) of 44 field experiments (All) and grouped according to season, district and crop selected. Treatments are ZBNF (green diamond), organic (orange square) and conventional (blue circle). Numbers in brackets show the number of farms (n= 3 per treatment, per farm). Season 1 (Kharif) data presented in Duddigan et al. (2022). Error bars represent standard error. Groups labelled with * have a significant treatment effect (ZBNF, organic, conventional) according to a REML mixed effects model (p < 0.05).

Fig. 3

Effect of farming practice on a soil moisture content, b soil temperature, c soil pH, d extractable K₂O, e extractable N and f total earthworm abundance across 3 seasons. Treatments are ZBNF (green diamond), organic (orange square) and conventional (blue circle). Error bars represent standard error. Treatments that share the same letter next to symbols in a particular season are not significantly different according to repeated measures ANOVA and LSD post hoc testing.