Comparison of Three Statistical Models Describing Potato Yield Response to Nitrogen Fertilizer

Abstract

Estimation of optimum fertilizer rates is of interest because of growing economic and environmental concerns. Optimum fertilizer rates can be determined by fitting statistical models to yield data collected from N fertilizer experiments. We evaluated quadratic, exponential, and square root models describing the yield response of potato (Solanum tuberosum L.) to six rates of N fertilization (0–250 kg N ha−1) with and without supplemental irrigation at four on‐farm sites in each of three years (1995 to 1997) in New Brunswick, Canada. Economic optimum N rates (Nop) varied among sites and models. The proportion of variability (R2) explained by the three models was similar. The quadratic model, however, calculated a greater Nop value (175 kg N ha−1) averaged over all sites than those calculated by the square root (123 kg N ha−1) and exponential (80 kg N ha−1) models. Regression residues of the quadratic model were closer to a normal distribution than those of the other two models, indicating a less systematic bias. Economic losses were greatest when the quadratic model was the most appropriate model, but the data were fitted to the exponential (loss of $204–240 ha−1; all values in Canadian dollars) or square root model (loss of $58–201 ha−1). We conclude that the quadratic model is the most appropriate for describing the potato yield response to N fertilizer and predicting Nop for areas with a ratio of the cost of N fertilizer to the price of potatoes similar to that in Atlantic Canada.

Predicting nitrogen fertilizer requirements of potatoes in Atlantic Canada with soil nitrate determinations

“…The Nop averaged over all sites was 175 kg N ha -1 (Bélanger et al 2000b), which is similar to the current general recommendation for N fertilization in Atlantic Canada (Bernard et al 1993). The Nop, however, varied greatly among sites (105 to 250 kg N ha -1 ).…”

“…In our study, the spring soil NO 3 -N content and Nop had a wide range, as reported previously (Bélanger et al 2000b). Therefore, the Nop and the range of soil NO 3 -N content should have been adequate to establish a satisfactory relationship.…”

“…The Nop was predicted with a quadratic model as previously reported by Bélanger et al (2000b). The quadratic model is presented as…”

Dose de nitrogênio associada à produtividade de batata e índices do estado de nitrogênio na folha

“…No Brasil, é possível encontrar recomendações de fertilização variando de 60 a 250 kg ha -1 de N (Fontes, 1999); a dose ótima a ser fornecida depende de vários fatores, como produtividade esperada, pluviosidade, cultura anterior, práticas culturais, entre outros (Fontes, 2001). Além disso, a dose a ser aplicada deve otimizar o rendimento da cultura e a qualidade final do produto, maximizar a rentabilidade e reduzir os riscos de contaminação ambiental (Bélanger et al, 2000).…”

Influência do fósforo na qualidade e produtividade de tubérculos de cultivares de batata de duplo propósito

“…A partir da equação ajustada para a produtividade comercial, em cada condição de disponibilidade de P no solo, foi calculada a dose de máxima eficiência econômica (DMEE), ou seja, a dose de P 2 O 5 (kg/ha) em que R$ 1,00 de P 2 O 5 adicional retornaria R$ 1,00 de batata produzida. A DMEE foi calculada igualando-se a derivada primeira de cada equação com a relação de preços do fertilizante fosfatado e da batata (Fontes et al, 1997;Bélanger et al, 2000). A relação de preços foi calculada considerando o preço médio (R$ 0,94/ kg) da batata comercializada em São Paulo durante o ano de 2011 (CEPEA/ ESALQ/USP, 2012) e o preço do P 2 O 5 do superfosfato triplo (R$ 4,46/kg).…”