Nitrogen requirement of wide-spaced row crops in the presence of starter fertilizer

Abstract. There is a need to develop sustainable nitrogen (N) management systems that minimize environmental losses by maximizing the use efficiency of applied fertilizers, particularly with wide-row annual crops that are often poor at utilizing N. A key approach is to match nitrogen supply with crop demand using improved methods of fertilizer application and timing. One technique is to target liquid 'starter' fertilizers close to the seed, or around the roots of transplants, and to omit or reduce conventional broadcast applications. This paper examines the effects of starter fertilizer combined with various rates of seedbed and/or top-dressed N on the growth and yield of bulb onion ( Allium cepa L.), crisp lettuce ( Lactuca sativa L.), forage maize ( Zea mays Bonaf.) and sugarbeet ( Beta vulgaris L.). Starter fertilizer improved early growth and, in combination with reduced rates of supplementary N, gave yields comparable with higher rates of base N with each crop, except sugarbeet. The use of top-dressed N was as effective as base N in supplementing starter fertilizer and had the benefit that it allowed a top-dressing requirement to be estimated accurately using a simple nitrogen balance equation. These results, taken with earlier work, show that starter fertilizers offer clear opportunities for reducing N inputs, while maintaining yield and quality of these crops.     

不同黄瓜品种对莴苣种子萌发化感作用的影响

以4个常见黄瓜品种(新津研4号、津旺1号、新4号、豫园春秀)为化感物质供体,以莴苣为化感物质受体,分别测定经黄瓜幼苗整株浸提液处理后的莴苣种子的发芽势、发芽率、发芽指数、活力指数、苗高、过氧化物酶、叶绿素含量、蛋白质含量等各项指标,并分析研究不同品种黄瓜幼苗整株浸提液对莴苣种子萌发和幼苗生长化感作用的差异.结果表明,与对照相比,莴苣种子的发芽率、发芽势、活力指数、发芽指数、苗高、叶绿素含量、蛋白质含量均显著下降,而POD活性则显著上升.而且各品种间相关指标差异均达到了显著水平,所以,不同品种黄瓜幼苗整株浸提液之间对莴苣种子的化感作用存在一定的差异,对供试材料中新津研4号化感作用最大,新4号、豫园春秀次之,津旺1号的化感作用最小.     

氯氰菊酯在茼蒿和油麦菜上的残留行为研究

为考察氯氰菊酯在茼蒿和油麦菜上的残留行为,于2016年在山西、山东、天津、安徽、云南和河南进行了氯氰菊酯在茼蒿和油麦菜上的规范残留田间试验。两种作物均包括6地的最终残留量试验和1地的消解动态试验。按照现行的蔬菜中拟除虫菊酯类农药残留测定的国家标准方法对样品进行检测,对方法的有效性进行了评价。田间试验结果表明:氯氰菊酯在茼蒿和油麦菜上的消解动态均符合准一级动力学方程,消解半衰期分别为3.2 d和1.8 d。最后一次施药3、5和7 d后,氯氰菊酯在茼蒿上的残留中值分别为1.64、1.19和0.89 mg/kg,在油麦菜上的残留中值分别为0.84、0.50和0.28 mg/kg。结合不同试验点试验期间昼夜平均气温发现,气温对氯氰菊酯在茼蒿和油麦菜上的残留量有明显影响。施药期间较低的气温下,氯氰菊酯在茼蒿和油麦菜上消解缓慢,残留风险明显增大。建议在实际生产中遇到低温天气应适当延长采收间隔期,另外在开展农药残留田间试验时应重视气象条件对残留试验结果的影响。     

多频超声波清洗机在叶类蔬菜清洗中的应用

清洗是蔬菜加工的关键环节,对品质至关重要.采用自行研制的超声及气泡式清洗设备对消费量较大的叶类蔬菜(生菜)进行清洗,以洗净率和破损率为指标,对清洗效果进行评价.结果表明,气泡式清洗在清洗时间40 s,洗菜量500 g条件下,生菜洗净率达到100％,此时破损率为12.89％;采用超声清洗时,在频率68 kHz,功率900 W,时间40 s,洗菜量750 g条件下,生菜洗净率为100％时,破损率为9.62％.可见当清洗时间相同,洗净率均达到100％时,超声清洗方式的洗菜量增加50％,破损率降低25.4％.因此,超声清洗方式更具优势.     

The effects of starter fertilizers on the growth and nitrogen use efficiency of onion and lettuce

Abstract. Broadcast granular fertilizers are inefficient at supplying nitrogen (N) to wide-spaced row crops. Substantial nitrate residues can remain in the soil post-harvest, even when recommended fertilizer practices are followed. This paper explores the benefits of an alternative strategy based on targeting small amounts of liquid nitrogen starter fertilizer close to the seed at drilling to increase N use efficiency and reduce potential pollution. Bulb onion ( Allium cepa ) and crisp lettuce ( Lactuca sativa ) were grown with various rates and combinations of ammonium phosphate (AP) and urea ammonium nitrate (UAN) as 'starters', in comparison with seedbed incorporated ammonium nitrate. AP consistently improved early growth and final yield of both crops compared to broadcast ammonium nitrate, but UAN showed no additional benefits. AP in combination with broadcast N, or injected UAN, generally increased N recovery, and produced yields of marketable quality produce matched only by much higher rates of broadcast N. A reduced N input system based on starter fertilizers is likely to be acceptable to the industry, but would rely on a method to predict how much N is required to supplement that provided by the starter.     

Effect of starter fertilizers on the yield and quality of lettuce grown on peaty soils

Abstract. Increasing concerns for the financial and environmental impact of the use of broadcast fertilizer by the UK horticultural industry is leading to the development of alternative application techniques, which aim to reduce inputs through improved efficiency. One such technique, 'starter' fertilizer, was investigated with drilled and transplanted crisp lettuce ( Lactuca sativa ) on two fertile peaty soils. Starter fertilizers injected below the seed of the drilled crop, or as spot applications around the planting module, were tested alone and in various combinations with different rates of broadcast fertilizer. The work extended previous findings, based largely on mineral soils, and demonstrated that high yields of iceberg quality lettuce can be achieved with reduced inputs of broadcast fertilizer, and that there can be additional benefits of earlier maturity and improved quality. It is concluded that starter fertilizer can contribute to the development of environmentally beneficial farming practices whilst maintaining the productivity and competitiveness of the horticultural industry.     

热激处理对鲜切莴笋色泽和质地的影响

为探究热激处理对鲜切莴笋色泽和质地的影响,以鲜切莴笋为材料,通过两因素三水平旋转中心组合试验,研究热激处理温度、处理时间对鲜切莴笋a*值、b*值、硬度、脆度、咀嚼性的影响,并在统计分析后,建立二次多项数学模型。结果表明,a*值、硬度、脆度、咀嚼性的回归模型都极显著,b*值不显著;热激处理温度是鲜切莴笋a*值的主要影响因素,处理时间是硬度、脆度、咀嚼性的主要影响因素;鲜切莴笋最佳热激处理条件为:温度49.52℃,时间13.14 min。在此条件下,鲜切莴笋达到最小a*值-12.97,最大硬度40.86 N,最大脆度44.69 N,最大咀嚼性17.96 m J。由此可见,实际应用中可采用处理温度50℃,处理时间14 min得到莴笋净菜良好的色泽和质构。本研究结果为鲜切莴笋热激处理提供了一定的技术依据。     

猪粪有机肥替代化肥对黄淮地区油麦菜品质及养分利用的影响

【目的】针对农村普遍存在的化肥施用过量、农产品质量下降和畜禽废弃物大量堆存等问题, 开展猪粪有机肥替代化肥试验。【方法】在黄淮地区选择典型种养结合区,采用田间小区试验方法,以 N 200.0 kg/hm2、 P2O5 96.8 kg/hm2 为参考施肥量（M）,研究了不同猪粪有机肥施加量（减量 50%M、M 和增量 100%M）及替代比例（0%M、25%M、50%M、75%M 和 100%M,以氮磷为基准）对油麦菜产量、品质和氮磷 利用率的影响,确定最佳施肥量和有机肥替代化肥的比例。【结果】在单独施加有机肥且施肥量小于参考施肥 量条件下,油麦菜产量、氮磷利用率随施肥量增加而增加;而继续增加施肥量,增产效果不显著,且品质及氮 磷利用率均有所下降。相同施肥量,有机肥部分替代化肥对油麦菜氮磷含量影响不显著,但可提高其产量、品 质及氮磷利用率。与化肥对照相比,当有机肥替代比例为 25%~75% 时,油麦菜硝酸盐和亚硝酸盐含量可降低 19.4% 和 73.3%（P ＜ 0.05）。有机肥替代比例为 75% 氮磷利用率为最高,较单施化肥提高 30.4% 和 44.9%。【结论】 采用参考施肥量 M 且有机肥替代比例为 75% 处理效果最优,不仅可保证油麦菜产量,还能有效提高品质和氮 磷肥利用率。研究结果可为区域蔬菜种植合理减量配施有机肥提供重要的科学依据,降低区域面源污染风险。