NPK removal from maize cultivation fields in Kenethao and Paklai districts, Xayabury province, Lao PDR

Abstract

The maize cultivation area in Lao PDR has increased since 2004, mostly without the use of fertilizer. For sustainable maize production, maintaining soil fertility is essential. This study aims to clarify nutrient removal by maize cultivation in fields located in the districts of Kenethao and Paklai in Xayabury Province-the main maize production area in Lao PDR. Field surveys were conducted at 27 plots in nine farmer fields in 2013 to measure maize production, collect plant samples for analyzing nutrient uptake and soil samples for analyzing nutrient stock in the soil, and interview farmers about cultivation practices and field history. N. P, and K removal by harvest from the fields totaled 51.7, 7.5, and 14.2 kg ha⁻¹. respectively. Nutrient stock in the soil surface layer at 0-20 cm deep was 2980 kg ha⁻¹ as total N. 10.1 kg ha⁻¹ as available P, and 233 kg ha⁻¹ as exchangeable K. N and K stocks in the soil were sufficient compared with N and K removal in maize at harvest, although available P in the soil was similar in amount compared to P removal by harvest. Most farmers did not apply any fertilizer for maize cultivation. The N. P, and K balances in the fields were estimated at -47.6. 7.4, and 14.3 kg ha⁻¹, respectively, without fertilizer input, and were improved to 25.6, +1.4. and +5.5 kg ha⁻¹ respectively, by applying chemical fertilizer.