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Proper irrigation scheduling in potato (Solanum tuberosumL.) can lead to higher returns and more sustainable production practices when compared to systems that do not take plant water demand into account. In an attempt to reduce irrigation applications while minimizing yield reduction, we evaluated a novel deficit irrigation treatment utilizing a mild irrigation reduction during tuber bulking by comparing a typical commercial irrigation schedule to a partial irrigation schedule. Physiological, yield, and quality effects were quantified. Reducing the number of irrigation applications by 14 in 2011 and by 9 in 2012 minimally affected most parameters measured. However, a significant yield reduction of 11,713 kg/ha in the partial irrigation treatment occurred in 2011, likely because of the irrigation treatment commencing at the latter portion of tuber initiation. In 2012, the initiation of the partial irrigation was delayed and resulted in no significant difference in yield between the partial and full irrigation treatments. This study shows the potential for a reduced irrigation schedule for use by Florida potato growers as a sustainable option for potato production in this region. [ABSTRACT FROM PUBLISHER]

Splitting N fertilizer application is recommended to increase crop N use efficiency by reducing risk of leaching. The objective of this study was to optimize the timing and rate of split N fertilizer applications to maximize tuber yield and quality of chipping potatoes grown using seepage irrigation in Florida. A two-year study was conducted on two commercial farms using cultivars Atlantic and FL1867. A factorial of two N rates applied at pre-plant (N pre-pl ) 0 or 56 kg ha −1 30 days before planting followed by four N rates applied at plant emergence (N emerg ) 0, 56, 112, or 168 kg ha −1 were randomized in a complete block design with four replicates. At tuber initiation, all treatments received an additional 56 kg ha −1 of N. All applications of N were of granular ammonium nitrate banded. Total N applied for the various treatments ranged from 56 to 280 kg ha −1 of N. Soil N was monitored in the 0–20 cm soil depth layer throughout the season. Whole plant biomass peaked at 8.5–8.7 Mg ha −1 with N emerg rates between 112–143 kg ha −1 . Plant N uptake range from 66 to 157 kg ha −1 . N uptake use efficiency decreased with increasing N rates. Potato yield ranged from 25 to 42 Mg ha −1 in both years. In 2013, application of 56 kg ha −1 of N pre-pl produced 2.5–5.1 Mg ha −1 higher yield than treatments receiving 0 N. In 2014, there was an interaction between N pre-pl and N emerg on yield. The higher 56 kg ha −1  N pre-pl resulted in higher yield only when N emerg was at or below 56 kg ha −1 . For cv. Atlantic when no N pre-pl was supplied, yield increased linearly in response to N emerg rates, while with 56 kg ha −1 of N pre-pl , yield responded quadratically to N emerg reaching a maximum at 114 kg ha −1 . For cv. FL1867 yield increased quadratically to N emerg peaking at 138 and 126 kg ha −1 of when 0 or 56 kg ha −1 of N pre-pl was applied, respectively. The study shows that while the risk of N pre-pl loss is high, N pre-pl can result in higher yield, especially when subsequent N rates are low. Application of N pre-pl was particularly effective in a dry year. By contrast, when soil mineral N from N pre-pl was largely lost to leaching in a high rainfall year, yield was increased by the N pre-pl application only when subsequent N emerg rates were less than 112 kg ha −1 . When early-season soil N was low, the N emerg had a larger impact on tuber yield due to minimum loss to leaching, maximizing yield when N emerg was 128–168 kg ha −1 . This indicates that applying N fertilizer prior to emergence is necessary to maximize tuber yield. [ABSTRACT FROM AUTHOR]

Soil physical quality indicator, Least Limiting Water Range (LLWR) is the range of soil water content, where water, oxygen and mechanical resistance are not limiting factors to root growth. The objective of this study was to evaluate LLWR, soil water availability, potato root growth and tuber yield under different water table management levels. Water table level was managed targeting 0.36 and 0.76 m below the soil surface, denoted as high (HI) and low (LO) level, respectively. Undisturbed soil core samples were obtained in the 0–0.15, 0.15–0.30 and 0.30–0.45 m soil layers to assess the LLWR. Root parameters were assessed using mini-rhizotrons installed into the soil along the potato row. Overall, LLWR decreased in depth due to a decrease in soil organic matter and an increase soil bulk density. The LO resulted in a narrower range for LLWR than HI. In the 0–0.15 m soil layer, the soil water content in the HI treatment fell inside the LLWR limits with high frequency during the growing season, but both water table levels resulted in similar root growth. In contrast, in the 0.15–0.30 and 0.30–0.45 m soil layers, soil water content fell inside LLWR more frequently in the LO than HI treatment. The LO management increased potato root length and surface area in the 0.15–0.30 m soil layer compared to HI; while in the 0.30–0.45 m soil layer, roots were not present in the HI likely due to the soil water content that was above LLWR. Optimal potato root growth was observed when the soil water content fell within the LLWR range at the highest frequency during the season. Despite impacts on the root system, similar tuber yields were achieved between LO and HI treatments. Nevertheless, the treatment HI used three times more water to supply the crop water requirement than LO. [ABSTRACT FROM AUTHOR]

Keeping soil moisture content at field-capacity in the root zone tends to maximize crop yield. However, this is challenging in sandy soils with a shallow water table and low water holding capacity. Seepage irrigation (SEP) relies on capillarity water movement from a water table to irrigate the crop, creating uneven soil moisture distribution across the field, which could be improved with drip irrigation. The objectives of this study were to evaluate irrigation water use efficiency (IWUE) for potatoes and soil moisture distribution uniformity of two drip tape installation depths (surface at 0.05 m, SUR and subsurface at 0.15 m, SUB) as an alternative method to SEP. The design of the experiment was a randomized complete block with irrigation treatments as main plots, and potato varieties (Atlantic, Fabula, and Red LaSoda) as subplots. The volume of water applied, water table level, and soil volumetric water content were continuously measured for two seasons, 2011 and 2012. Drip irrigation significantly increased the moisture distribution uniformity in the potato ridge. The majority of the plant root system was concentrated in the upper soil layer (∼0.3 m), regardless of irrigation treatment. Similar marketable yield between SUR and SEP were achieved for Fabula and Atlantic in the first season, while lower yields were reported for Red LaSoda under drip in both years. The SUB produced lower yield in both years attributed to limited water capillarity. Drip irrigation reduced water use 48% and 88% in 2011 and 2012, respectively. Higher IWUE was obtained with drip compared to SEP for all varieties in 2012. The SEP used more irrigation water to supply the crop than SUR resulting in a difference in IWUE of 5.7 kg m −3 . The SUR was capable of adequately irrigating the potato shallow root producing similar yield to SEP for Atlantic and Fabula varieties. [ABSTRACT FROM AUTHOR]