An Improved Model of Nitrogen Release for Surface‐applied Controlled‐release Fertilizer

Abstract

Empirical temperature models are commonly used to estimate N release from polymer‐coated controlled‐release fertilizers (CRFs) under field conditions where the influence of soil moisture is negligible. For surface‐applied CRF in bare‐root nurseries, the effect of soil moisture may be important. To quantify the effect of soil moisture on N release from surface‐applied CRF, two experiments were conducted in a sandy‐textured soil: (i) a laboratory experiment to develop two semiempirical models that characterized the effect of soil temperature (T model) and moisture (MT model) on N release, and (ii) a field experiment to evaluate the precision of these models. In the laboratory experiment, the N release from CRF (urea, 41–0–0, ∼2‐mo release) was measured under 16 combinations of four soil temperatures (5, 10, 23, and 35°C) and four soil moisture contents (0.002, 0.04, 0.11, 0.22 kg kg−1). The calculated time constants for each abiotic combination showed that both soil temperature and soil moisture content controlled the cumulative N release (CNR). The difference between model estimates and field measurements of CNR indicated that the T model significantly underestimated CNR by as much as 18% (P < 0.01). In contrast, this difference was reduced to 8% using the MT model; the slope of the least‐square fit for the MT model was not significantly different from unity at the 1% level and just significant at 5% (P = 0.052). Therefore, we argue that a model parameterized by both soil temperature and soil moisture will improve estimates of CNR from surface‐applied CRF in irrigated tree nurseries.

Nitrogen Fertilizer Sources and Application Timing Affects Wheat and Inter-Seeded Red Clover Yields on Claypan Soils

“…Polymer-coated urea is a controlled-release enhanced efficiency fertilizer product that encases urea in a polymer coat. After urea dissolves within the prill, it diffuses out at varying rates depending on soil temperature [8,9]. NBPT can enhance the efficiency of a urea application and avoid ammonia volatilization losses due to reduced activity of the urease enzyme [10].…”

Nitrogen Release Dynamic of Different Coated Urea under Puddle Lowland Rice Cultivation

“…Moisture is another factor that affects the rate, pattern and duration of release of nitrogen from coated urea (Fujinuma et al, 2009;Shaviv, 2005) (Table 1). However, since the trail was conducted under irrigated condition, the effect of moisture remained neutral for all the treatments.…”

“…Temperature and moisture are two climatic factors that affect the rate, pattern and duration of release of nitrogen from coated urea (Fujinuma et al, 2009;Shaviv, 2005).…”

Corn Response to Nitrogen Management under Fully‐Irrigated vs. Water‐Stressed Conditions

“…The use of specialized "controlled-release" N fertilizer sources, including PCU and urea amended with IU, has the potential to minimize NO 3 -leaching (Wilson et al, 2010;Zvomuya et al, 2003) and nitrous oxide emissions (Halvorson et al, 2010;Hyatt et al, 2010). There is some concern, however, about the effectiveness of PCU and IU under dryland conditions because of erratic release rates with fluctuating soil moisture (Fujinuma et al, 2009) and studies showing limited or no effectiveness (Sistani et al, 2011;Venterea et al, 2011). It is not well understood how the agronomic effectiveness of controlled-release N sources may be affected by variation in water availability or management.…”