Nitrogen Use as a Component of Sustainable Crop Systems

Riar, Amritbir; Coventry, David

doi:10.1016/b978-0-12-404560-6.00004-6

Cited by 4 publications

(5 citation statements)

References 58 publications

(51 reference statements)

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“…Comparing the P availability among two management systems at all the five sampling times, we can conclude that P availability was not a limiting factor for organic at any of these time points. However, utilization of available P by crop plants depends on several factors and N availability could be one of them ( Riar and Coventry, 2012 ). Since soybean can symbiotically assimilate atmospheric nitrogen, probably it had relatively higher capability of utilizing available P compared to wheat.…”

Section: Discussionmentioning

confidence: 99%

Soil Biological Activity Contributing to Phosphorus Availability in Vertisols under Long-Term Organic and Conventional Agricultural Management

et al. 2017

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Mobilization of unavailable phosphorus (P) to plant available P is a prerequisite to sustain crop productivity. Although most of the agricultural soils have sufficient amounts of phosphorus, low availability of native soil P remains a key limiting factor to increasing crop productivity. Solubilization and mineralization of applied and native P to plant available form is mediated through a number of biological and biochemical processes that are strongly influenced by soil carbon/organic matter, besides other biotic and abiotic factors. Soils rich in organic matter are expected to have higher P availability potentially due to higher biological activity. In conventional agricultural systems mineral fertilizers are used to supply P for plant growth, whereas organic systems largely rely on inputs of organic origin. The soils under organic management are supposed to be biologically more active and thus possess a higher capability to mobilize native or applied P. In this study we compared biological activity in soil of a long-term farming systems comparison field trial in vertisols under a subtropical (semi-arid) environment. Soil samples were collected from plots under 7 years of organic and conventional management at five different time points in soybean (Glycine max) -wheat (Triticum aestivum) crop sequence including the crop growth stages of reproductive significance. Upon analysis of various soil biological properties such as dehydrogenase, β-glucosidase, acid and alkaline phosphatase activities, microbial respiration, substrate induced respiration, soil microbial biomass carbon, organically managed soils were found to be biologically more active particularly at R2 stage in soybean and panicle initiation stage in wheat. We also determined the synergies between these biological parameters by using the methodology of principle component analysis. At all sampling points, P availability in organic and conventional systems was comparable. Our findings clearly indicate that owing to higher biological activity, organic systems possess equal capabilities of supplying P for crop growth as are conventional systems with inputs of mineral P fertilizers.

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Section: Discussionmentioning

confidence: 99%

Soil Biological Activity Contributing to Phosphorus Availability in Vertisols under Long-Term Organic and Conventional Agricultural Management

et al. 2017

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“…1) (Krause and Cooper, 2011). Usually more rain falls in the early growing period and less in the late growing period of wheat crop and the dependence on stored water accumulated over winter becomes increasingly important to crop growth and yield as the season progresses (Riar and Coventry, 2013). As observed in these experiments, the timing and amount of rainfall is variable and large seasonal differences in yield can occur.…”

Section: Discussionmentioning

confidence: 99%

“…Nitrogen fertilizer application can lead to considerable increases in wheat grain yields, but NUE (net yield increase per unit N applied) is frequently low. Nitrogen fertilizer is generally applied early in the season, either just before or at sowing, or during the first few weeks after sowing (Riar and Coventry, 2013). The advantages of early N applications include improvements in crop early vigor, increased weed competition and ultimately improvements in grain yield and quality.…”

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confidence: 99%

“…Soil available water plays a very important role in N recovery by plants. Excess soil available water can lead to various losses of N, and its absence inhibits N uptake (Riar and Coventry, 2013). More importantly, the timing of N application could affect the balance of soil water storage during the growing season by influencing canopy transpiration area (Heidmann et al, 2000; Nakano et al, 2008).…”

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confidence: 99%

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Use of Nitrogen Fertilizer in a Targeted Way to Improve Grain Yield, Quality, and Nitrogen Use Efficiency

Hooper¹,

Zhou

Coventry

et al. 2015

Agronomy Journal

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Nitrogen fertilizer management in rainfed Mediterranean environments can be nancially risky because of the strong interaction between N and water availability on yield. is study was conducted to investigate whether the use of split-applications of N fertilizer that targeted speci c growth stages could improve grain yield, grain protein concentration (GPC), and nitrogen use e ciency (NUE) of dryland wheat (Triticum aestivum L.). Experiments with 7 N-application timings, two N-rates, and two wheat varieties were conducted at two sites over two seasons. Despite the seasonal rainfall in both years being below the historic averages, delayed or split N applications were able to signi cantly increase grain yield (2.50 vs. 2.25 t ha -1 ), GPC (14.0 vs. 12.4%), N uptake (111.2 vs. 101.2 kg ha -1 ), N harvest index (70.7 vs. 61.7%), agronomic e ciency (4.6 vs. 1.7 kg kg -1 ), and apparent recovery (59.3 vs. 44.6%) compared with N applied only at sowing. No single N treatment was able to consistently produce the highest yield, GPC or NUE across the N rates, locations, and years because of the in uence of timing and amount of rainfall during the season. Compared with applying all the N at sowing a targeted use of N, using split/delayed N applications at speci c growth stages to manage canopy development in response to the seasonal pattern of rainfall, increased yield, quality, and NUE, even in years with below average rainfall, thus lessening exposure to nancial risk with rainfed wheat in dry years.

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“…Nitrogen intake plays a very important role in plant development (Herridge et al, 2008;Xu et al, 2012). Chemical N input can increase protein amount in plants and result in changes of plant nutrient and plant shape characteristics (Riar & Coventry, 2013). However, many researchers have reported that chemical N application is linked with the occurrence of certain insect pests (Jauset et al, 1998;Nevo & Coll, 2001;Men & Kandalkar, 2002;Wang et al, 2007;Ge et al, 2010;Pang & Dong, 2012).…”

Section: Discussionmentioning

confidence: 99%

Impacts of nitrogen fertilizer on major insect pests and their predators in transgenic Bt rice lines T2A‐1 and T1C‐19

Yang

Liu

Han

et al. 2016

Entomologia Exp Applicata

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Nitrogen is a critical factor for plant development and nitrogen input is one of the important tactics to enhance the development and yield of crops. Nevertheless, nitrogen input could influence the occurrence of insects positively or negatively. Nitrogen is also one of the main elements composing the insecticidal crystal (Cry) protein. Cry protein production could affect nitrogen partitioning in Bt plants and as such nitrogen input may influence insect pest management in transgenic Bt rice, Oryza sativa L. (Poaceae). To test this possibility, we evaluated the impacts of nitrogen regimes on the main insect pests and their predators on two Bt rice lines, T2A-1 and T1C-19, expressing Cry2A and Cry1C, respectively, and their non-transgenic parental counterpart MH63. The results showed that Cry proteins with different nitrogen regimes have enough insecticidal activity on rice leaffolder, Cnaphalocrocis medinalis Guen ee (Lepidoptera: Crambidae), in both laboratory and field experiments. Laboratory studies indicated that relevant parameters of ecological fitness in brown planthopper, Nilaparvata lugens (St al) (Hemiptera: Delphacidae), a non-target insect pest, were significantly affected by nitrogen input both on Bt and MH63 rice lines. Nymphal survival, female adult longevity, and egg hatchability in N. lugens differed significantly among rice varieties. The experiments conducted in rice fields also demonstrated that nitrogen was positively correlated with the abundance of N. lugens on Bt rice, similar to that on MH63 rice. The abundances of two predatorsthe wolf spider Pirata subpiraticus (Boesenberg & Strand) (Araneae: Lycosidae) and the bug Cyrthorhinus lividipennis Reuter (Hemiptera: Miridae)were significantly affected by rice growth stages but not by nitrogen input and rice varieties. In conclusion, the above results indicate that high nitrogen regimes for Bt rice (T2A-1 and T1C-19) and non-Bt rice (MH63) cannot facilitate the management of insect pests.

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Nitrogen Use as a Component of Sustainable Crop Systems

Cited by 4 publications

References 58 publications

Soil Biological Activity Contributing to Phosphorus Availability in Vertisols under Long-Term Organic and Conventional Agricultural Management

Soil Biological Activity Contributing to Phosphorus Availability in Vertisols under Long-Term Organic and Conventional Agricultural Management

Use of Nitrogen Fertilizer in a Targeted Way to Improve Grain Yield, Quality, and Nitrogen Use Efficiency

Impacts of nitrogen fertilizer on major insect pests and their predators in transgenic Bt rice lines T2A‐1 and T1C‐19

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