Water and nutrient management are essential to achieve high yield and desirable quality attributes in processing tomato (Lycopersicon esculentum Mill.). A 4-yr fi eld study (2006)(2007)(2008)(2009) was conducted to assess eff ects of contrasting water management (dripirrigation vs. nonirrigation), fertilizer P (0, 30, 60, and 90 kg P ha -1 ), and K (0, 200, 400, and 600 kg K ha -1 ) on yields and quality of processing tomato when the optimum N rate of 270 kg N ha -1 was applied. Compared with nonirrigation, drip irrigation increased marketable fruit yield by 127%, total fruit yield by 66%, and fruit size by 32%, while it decreased soluble solids content (SSC) by 19% and lycopene content by 8%, with no eff ects on dry biomass of stems and leaves (DBSL). Phosphorus addition had no eff ects on marketable yield and SSC, but increased the DBSL and lycopene content to maximum values at 60 kg P ha -1 . Fertilize K rate aff ected all examined variables but the lycopene content. Increasing K rates from 0 to 200 kg K ha -1 increased marketable fruit yield by 10% and total fruit yield by 9%, but fruit size declined by 3%. Increasing K rates from 200 to 600 kg K ha -1 , however, had no eff ects on yield and fruit size. Fertilizer K rate had no eff ects on SSC with nonirrigation, but resulted in a linear increase in SSC with drip-irrigation. Th e results suggested that, with optimum N supply, K application is required to increase fruit yield and quality of drip irrigated processing tomato.

Agronomic and economic assessments of response of processing tomato (Lycopersicon Esculentum Mill.) to nutrient application with drip fertigation are essential to optimize soil fertility management that maximizes farmers' profi tability in a sustainable manner. A fi eld study was conducted to evaluate the yield and economic responses of drip fertigated processing tomatoes to additions of fertilizer nitrogen (N) and phosphorus (P) from 2003 to 2005. Th e experiment was arranged in a factorial design with four levels of fertilizer N (0, 120, 240, and 360 kg N ha -1 ) and three levels of fertilizer P (0, 100, and 200 kg P 2 O 5 ha -1 ). Fertilizer N application aff ected biomass yield of stems and leaves, total and marketable fruit yields, N use effi ciency, and N agronomic effi ciency. However, neither P application nor the interaction between fertilizer N and P infl uenced these variables. Nitrogen use effi ciency and N agronomic effi ciency decreased with increases in fertilizer N rate, with N use effi ciency averaging 443 kg kg -1 and N agronomic effi ciency averaging 237 kg kg -1 . Both fruit yields and net economic returns responded quadratically to the fertilizer N rate, with a maximum marketable yield of 127 Mg ha -1 averaged across the 3 yr. Th e fertilizer N rates were 271 kg N ha -1 for the maximum marketable yield and 265 kg N ha -1 for the optimum economic yield. Th ese values are considerably greater than the current recommendation, due to the largely increased yield with drip fertigation. Fertilizer N should be applied at an increased rate for processing tomatoes with drip fertigation to maximize the economic return.

Titnely sufficient water supply through drip irrigation or fertigation may increase nutrient demand of processing tomato {Lycopersicon esculentum Mill.) due to increases in yield production. However, excessive nutrient application could result in crop Itixury uptake and enrichment in soil profile, especially mineral N, with the latter potentially causing environmental concerns. A study was conducted to determine the responses of crop N utilization and post-harvest soil profile mineral N to fertilizer N and P additions under drip fertigated processing tomato in sandy loam soils from 2003 to 2005. Across the 3 yr, both fruit N removal and plant total N uptake were either linearly or quadratically related to fertilizer N rate, with 187 kg N ha" ' of fruit removal and 268 kg N ha" ' of plant total N uptake obtained at the maximum yield. Nitrogen uptake efficiency and apparent N recovery decreased linearly with increases in N rate. At the maximum fruit yield, N uptake efficiency was 0.71, and apparent N recovery was 51.7%. Post-harvest soil profile (0-100 cm) mineral N increased with increases in fertilizer N rate, and at greater rates with fertilizer N appHed at rates above those required for maximum fruit yield production. Of the soil residual N, 62% remained in the top 40-cm soil layer. Addition of fertilizer P had no effects on plant N uptake, N uptake efficiency and post-harvest mineral N in soil profile, presumably due to the high levels of soil test P. Beneficial management practices need to be developed to prevent soil N losses during the non-growing season following production of processing tomato with drip fertigation.

Processing tomato phosphorus utilization and post-harvest soil profile phosphorus as affected by phosphorus and potassium additions and drip irrigation. Can. J. Soil Sci. Sci. 91: 417Á425. Phosphorus (P) applied in agricultural land not only affects crop P utilization, but can also cause environmental concerns when excessive P applied moves off-site to surrounding water systems. A 2-yr study, 2007Á2008, was conducted to determine the effects of fertilizer P (four rates: 0, 30, 60, and 90 kg P ha (1) and potassium (K) (four rates: 0, 200, 400, and 600 kg K ha (1) additions and drip irrigation on crop P utilization and post-harvest agronomic (i.e., Olsen P) and environmental [i.e., water extractable P (WEP)] soil test P under processing tomato in loamy sand soils. Plant P uptake increased, but apparent P recovery decreased with increases in fertilizer P rate. Cumulative soil WEP in the 0-to 100-cm soil profile and Olsen P in the 0-to 20-cm depth increased linearly with increases in fertilizer P rate, regardless of water management. No effects of K were found on plant P utilization, soil WEP, or soil Olsen P. Drip irrigation increased plant P uptake by 35% and apparent P recovery by 44%, relative to non-irrigation. Drip irrigation consequently decreased the post-harvest soil profile WEP by 14% and Olsen P by 6.5% averaged across the 2 yr, compared with non-irrigation. Drip irrigation reduced the potential for post-harvest soil P losses by improving P utilization. the addition of fertilizer P needs to be optimized by considering crop P needs in association with actual yield production to ensure processing tomatoes are produced in an environmentally sustainable manner.

Drip fertigation is an effective way in splitting soluble fertilizer application to simultaneously meet water and nutrient demands of multi‐harvested green pepper (Capsicum annuum L.). However, fruit yield and the profitability of green pepper can be constrained, if nutrients are either insufficiently or excessively supplied. A 3‐yr experiment was conducted to assess both agronomic and economic effects of fertilizer N and P addition for green pepper grown under drip fertigation. Both fruit yields, including total and marketable, and net economic return responded quadratically to fertilizer N rate. The 3‐yr average maximum marketable yield of 38 Mg ha−1 was achieved at the N rate of 227 kg N ha−1 The economic optimum N rate was identical to the one required for the production of maximum marketable yield, due to the large price ratio of green pepper to fertilizer N. Nitrogen use efficiency and N agronomic efficiency decreased as N rate increased. The amount of fertilizer N required for production of each megagram of marketable fruit yield increased with the level of yield, with an average of 6.0 kg N Mg−1 fruit across the 3 yr at the maximum marketable yield. Fertilizer P did not affect selected variables, except for both total and marketable fruit yields that increased linearly with increases in P rate in one of the 3 yr. The results suggested that an increase in the optimum N rate to 227 kg N ha−1 is needed to maximize the profitability of green pepper production with drip fertigation