Long‐term phosphate fertilization strategies evaluation in a Brazilian Oxisol

Abstract

There are concerns related to the application of phosphate fertilizers to weathered soils that present low soil test phosphorus (STP) due to P adsorption in iron oxyhydroxides. Furthermore, long-term trials are needed to evaluate crop response to corrective P fertilization and its interaction with different maintenance P fertilization strategies in these soils. An experiment involving the combination of three initial corrective P fertilization schemes (control without P correction or with the application of 105 kg P ha −1 as triple superphosphate [TSP] or reactive rock phosphate [RRP]), four P maintenance strategies (a control without the application of maintenance P, or 35 kg P ha −1 yr −1 as TSP, RRP, or a mix of both) and two application methods was cultivated during 16 yr at the Embrapa Cerrados experimental station in Planaltina, DF, Brazil. Corrective P fertilization promoted an early crop yield response. In contrast, high crop yields were only obtained in control treatments with no corrective P fertilization after soil P stocks were increased to a minimum level. With increasing P stocks, broadcast application resulted in slightly better yields. The required residual P stocks in soil to obtain high yields were estimated as equivalent to 113.6 and 205.2 kg P ha −1 for TSP and RRP, respectively. These values allow for STP contents to increase to critical levels, whose value for TSP of 4.1 mg kg −1 Mehlich-1 P is below that recommended for the region, possibly due to the contribution of organic P forms in the long-term no-tillage system.

Corrective and maintenance phosphorus fertilization on sugarcane yield in Oxisols

“…This corrective fertilization is justified by the well-known and long residual effect of phosphorus application, which, in the case of annual crops, seems to be even more pronounced under no-tillage management (Sousa et al, 2016;Oliveira et al, 2019), a condition analogous to sugarcane ratooning. Under no-tillage, the long term recovery of broadcast-incorporated phosphorus in harvested products reached nearly 80% in a clayey Oxisol (Oliveira et al, 2020). Contrary to previous views that applied phosphorus is largely converted to forms unavailable to the plant, particularly in highly weathered soils, current analyses based on worldwide long-term experiments have pointed out that, once the soil phosphorus critical level is reached, phosphorus use efficiency by crops can exceed 80-90%, sustaining near maximum yields in the long run (Syers et al, 2008;Johnston et al, 2014).…”

Distribution of Soil Phosphorus Fractions as a Function of Long-Term Soil Tillage and Phosphate Fertilization Management

“…In fact, this was observed by de Oliveira et al (2020b) after cultivating this area without P input during successive corn crops, where despite about 100% of crop nutrition was supplied by the 0-5.0 cm layer under broadcast P application, compared to 70% under band application, P offtake and grain yield were similar between both application methods. Continuous broadcast P fertilization under NT could even increase yields in highly adsorptive weathered soils (de Oliveira et al, 2020a).…”

“…The reason is that Cerrado soils have a high solid phase P retention capacity, due to their high Fe and Al sesquioxide constitution, capable of retaining phosphate ions in less labile forms (Fink et al, 2014(Fink et al, , 2016a. Consequently, a high fertilizer P input, at a rate above that exported by the crop harvested products, is demanded when establishing the cropping system under these low initial soil test P (STP) soils, to improve P contents and compensate the soil solid phase P sink (de Oliveira et al, 2020a), which is significantly higher than plant demand (Novais et al, 2007). This high P input is usually called corrective P fertilization, and P rates depend on STP and soil buffer capacity (Sousa et al, 2010).…”