Evaluating regional mean optimal nitrogen rates in combination with indigenous nitrogen supply for rice production

On-farm trials of optimal fertilizer recommendations for the maintenance of high seed yields in winter oilseed rape (Brassica napus L.) production

“…It is difficult to determine the optimal N fertilizer application rate for varied soil N levels due to the weak relationship between soil total N content and relative yield, which agreed with the previous studies (Cassman et al 1996;Wang et al 2012). Nevertheless, the highly Figure 4 The relationship between plant available soil nutrient supply and seed yield of the nutrient omission treatment.…”

“…Considering how laborious it is to determine plantavailable soil N supply, seed yield of the 0-N treatment was an acceptable index. Furthermore, the significant correlation between plant-available soil N supply and seed yield of the 0-N treatment also demonstrated that seed yield could be used to describe plant-available soil N supply (Wang et al 2012). When the seed yields of the 0-N plot exceeded 2000 kg ha…”

“…AFE is expressed in % and AE is expressed in kg kg −1 . According to the previous studies (Brennan and Bolland 2007;Wang et al 2012), a logarithmic function is used to describe the relationship between soil nutrient supply (soil nutrient testing, plant-available soil nutrient supply and seed yield of the nutrient omission treatment) and the relative yield, and to estimate the yield responseto fertilizer recommendation. If the relative yield is less than 50%, then the soil nutrient supply is "extremely deficient" and fertilizer application will enhance seed yield significantly.…”

“…Compared with the N cycle, the phosphorus (P) and potassium (K) cycles in soils are relatively simple, and the indices of soil phosphorus and potassium supply, such as Olsen-P (Ding et al 2014) and NH 4 OAc-K (Mallarino et al 2003), have been accepted widely. Besides soil testing, plant-available soil nutrient supply, which was defined as nutrient uptakes measured in the nutrient omission plots (plots without fertilizer application of one of the key macronutrients) (Wang et al 2001) and crop yields in nutrient omission plots (Wang et al 2012) have also been proposed as an applicable approach for advancing fertilizer recommendation rates. Depending on the grain yield in the N-omission plot, the N RMOR of rice (Oryza sativa L.) was optimized further according to the specific conditions of each region (Wang et al 2012).…”

Potential of VIS-NIR-SWIR Spectroscopy from the Chinese Soil Spectral Library for Assessment of Nitrogen Fertilization Rates in the Paddy-Rice Region, China

“…According to statistics from the FAO [1] there were 150.8 million of people undernourished in China from 2012 to 2014. Among existing agricultural practices, the application of N fertilizer has gained increasing popularity, and has played a major role in significantly increasing crop yield, especially in intensive paddy-rice systems [2]. This is because rice, which grows under flooded low-land conditions in paddies, is a key staple food for daily consumption in China, making up about 43.7% of the total national grain production [3].…”