Efficiency Indexes for Melon Crop Optimization

Abstract

Th e present study reviews the most common N effi ciency indexes with a view to maximizing yield and minimizing N loss, for melon grown in a zone where the water supply has a high nitrate content due to environmental degradation. Th e N use effi ciency (NUE) values of the study were those relating the fruit yield (FY) and the dry weight (DW) with N applied (N ap ), N available (N av ), and N uptake (N up ), which were denominated NUE 1 , NUE 2 , NUtE, NUE 3 , NUE 4 , and NUE 5 , respectively. A 3-yr fi eld experiment (2005, 2006, and 2007) was performed from May to September in central Spain. Melon crops were irrigated at 100% of the ET c (crop evapotranspiration) and 11 N rates, ranging from 11 to 393 kg ha -1 (considering N fertilizer [N f ], applied over 10 wk, and N in the irrigation water [N w ], where the NO 3 concentration was 5.58, 80.64, and 10.89 mg L -1 in 2005, 2006, and 2007, respectively), were applied to a soil classifi ed as Alfi sol Xeralf Petrocalcic Palexeralfs. Th e results show a clear relationship between crop N up and both FY and DW. Of the potential yield, 95% could be obtained with a N application of 93 kg ha -1 . Th e maximum FY was observed with a N up of 155 kg ha -1 . Th e NUE, when related to N ap and N av , showed an exponential trend and when related to N up a linear trend, delimiting a range within which the optimum value of N occurs.

Growth dynamics and yield of melon as influenced by nitrogen fertilizer

“…As a result of this inverse response, a similar accumulation of the total biomass in the three treatments over the entire crop cycle was obtained (Figure 3d). This could be due to the fact that the N uptake in the N 93 treatment was close to the threshold value of N uptake by melon crop (180 kg ha -1 , in our case) (Castellanos et al, 2010). In 2007, the amount of N influenced (p < 0.05) from 50 DAT leaf and stem dry weights and from 64 DAT (Figure 4a, b and d).…”

“…Its growth dynamics is different from types of melon already studied and also, the N optimization in relation to growth and yield. In fact, large amounts of N are used by growers (sometimes higher than 250 kg ha -1 ) contributing to the increase of the contamination of groundwater by nitrates (Castellanos et al, 2010).…”

Scale and space dependencies of soil nitrogen variability

“…The rainfall was negligible during the crop experiment, so the water applied was calculated as the ratio between the ETc of the previous week and the efficiency of the system, which considers the salt tolerance of the crop, the quality of the irrigation, the soil texture and the homogeneity of the irrigation system (Rincón and Giménez, 1989), estimated as 0.81 under the study conditions (more details in Castellanos et al, 2010). The irrigation calculated in this form was the theoretical irrigation and was divided by the number of days to obtain daily irrigation requirements.…”

“…These two units, Mancha Occidental (UH04.04, 6.953 km 2 ) and Campo de Montiel (UH04.06, 3192 km 2 ), have been declared vulnerable zones to nitrate pollution with high NO 3 contamination problems. In the first experiment, the plots were used for melon crop experiments to optimize fertigation using different levels of N, as reported in Castellanos et al (2010). These treatments constituted a known contribution to the variation of soil nitrogen at predominantly larger scales.…”

“…This work is the first application of both types of analysis to the same data set. The area is characterized by a continental Mediterranean climate with widely fluctuating daily temperatures (for more details, see Castellanos et al, 2010).…”