Substitution of inorganic fertilizers with organic manure reduces nitrate accumulation and improves quality of purslane

Growers often apply high amounts of chemical fertilizers for vegetable production and this application contributes to concerns about nitrate levels in food. An experiment was conducted to investigate soil N amendment effects for reducing the nitrate accumulation and improving the quality of fresh purslane (Portulaca oleracea L.). Treatments included four levels of animal manure as follows, N-based broiler litter (T1), P-based broiler litter (T2), N-based cattle manure (T3), P-based cattle manure + urea (T4), four levels of chemical fertilizer equivalent to organic treatments, and a T0 (no fertilizer and manure). Results showed that nitrate levels of broiler litter and cattle manure treatments were significantly lower than those of chemical fertilizer treatments. The highest level of nitrate in the first harvest was recorded in the T7 treatment and higher levels were recorded in T5 and T7 treatments in the second harvest. In the first harvest, T1 and T2 treatments had higher appearance quality but in the second harvest, appearance quality of T2 and T5 treatments showed a significant increase compared to the other treatments. It is concluded that organic manure application results in higher quality as compared with the inorganic fertilizer andreduces nitrate accumulation in fresh purslane.