Impact of long-term fertilization, straw incorporation and liming on phosphorus fractions, availability and their interactions with soil properties in red soil
Lehlogonolo Abner Matelele, Naiyu Zhang, Xian-Mei Zhang, Christian Kofi Anthonio, Ashraful Alam, Huimin Zhang, Zhang Shuxiang
Abstract
Investigating the contributions of different soil properties and their influences on changes in soil P fractions and availability is helpful for soil P management. Soil samples were collected in 2018 from a long-term red soil field experiment established in 1990. The unfertilized control (CK), chemical NK, NP, NPK, NPK with straw (S) (NPKS), NK + lime, NP + lime, NPK + lime, and NPKS + lime fertilization treatments, which were arranged in a randomized complete block design, were selected. Compared with no lime, lime addition significantly increased the labile P/total P ratio in the NPK and NPKS treatments by 12.35% and 11.75%, respectively. The results further revealed that fertilization treatments without lime application (NK, NP, NPK, and NPKS) significantly reduced the soil pH, Mehlich-3 (M3)-Mg and M3-Ca compared with those in the CK and lime treatments during 2018. In contrast, lime application reduced the M3-Fe and M3-Al concentrations by 2% and 3%, respectively. Long-term P fertilization improved soil organic matter, M3-P, M3-Fe, and M3-Al. While soil pH exhibited a strong and positive relationship with M3-Mg (r = 0.780**) and M3-Ca (r = 0.788**) and a strong and negative correlation with M3-Fe (r = -0.395*) and M3-Al (r = -0.584**), the transformation and discharge of various P pools in red soil were facilitated by soil OM, M3-Fe, and M3-Al as the key contributors. NPK and NPKS combined with lime addition could be useful approaches for increasing the available P (labile P/total P) by enhancing M3-Ca and M3-Mg and soil pH while reducing M3-Fe and M3-Al in red acidic soil.