Mizuhiko Nishida

Status of paddy soils as affected by paddy rice and upland soybean rotation in northeast Japan, with special reference to nitrogen fertility

To investigate the current available nitrogen (N) and chemical properties of paddy soils affected by crop rotation between irrigated paddy rice (Oryza sativa L.) and upland soybean [Glycine max (L.) Merr.] (paddy-upland rotation), topsoils were collected from 22 fields of four different farmers in the northeastern region of Japan. Regardless of organic material application, a significant negative correlation was found between available soil N and an increase in the proportions of upland seasons to total crop seasons after the initiation of paddy-upland rotation. Soil total N and total carbon (C) also tended to decrease with an increase in upland frequency. In fields with repeated applications of cattle manure compost, the soil available N was higher than in fields where only crop residue was applied. A significant negative correlation was also found between the soil available N:total N ratio and upland frequency. This indicates that the part of soil N related to available N was notably lost by the use of paddy fields as upland fields. In order to sustain available soil N over the minimum suitable level of 80 mg kg−1, upland frequency should not exceed 65% when only crop residues and no other organic materials are applied. The upland frequency can be raised by the repeated application of organic materials which maintain a higher level of available soil N. The results imply that care should be taken to maintain the N fertility of paddy soil at a suitable level in paddy-upland rotation, and that upland frequency and organic materials applied are important factors to do this.

Changes in natural 15N abundance in paddy soils under different, long-term soil management regimes in the Tohoku region of Japan

Abstract Long-term temporal changes in natural 15N abundance (δ15N value) in paddy soils from long-term field experiments with livestock manure and rice straw composts, and in the composts used for the experiments, were investigated. These field experiments using livestock manure and rice straw composts had been conducted since 1973 and 1968, respectively. In both experiments, control plots to which no compost had been applied were also maintained. The δ15N values of livestock manure compost reflected the composting method. Composting period had no significant effect on the δ15N value of rice straw compost. The δ15N values increased in soils to which livestock manure compost was successively applied, and tended to decrease in soils without compost. In soils to which rice straw compost was successively applied, the δ15N values of the soils remained constant. Conversely, δ15N values in soils without rice straw compost decreased. The downward trend in δ15N values observed in soils to which compost and chemical N fertilizer were not applied could be attributed to the natural input of N, which had a lower δ15N value than the soils. Thus, the transition of the δ15N values in soils observed in long-term paddy field experiments indicated that the δ15N values of paddy soils could be affected by natural N input in addition to extraneous N that was applied in the form of chemical N fertilizers and organic materials.

Kinetics of 15N-labelled nitrogen from co-compost made from cattle manure and chemical fertilizer in a paddy field: Effect of mixing ratio of cattle feces and ammonium sulfate

Abstract In order to produce an effective organic fertilizer for plant uptake and to examine the characteristics of a nitrogen fertilizer, cattle feces and (NH4)2SO4 were co-composted, and the kinetics of nitrogen uptake by rice plants from the co-compost was traced by the use of 15N. Cattle feces and (NH4)2SO4, either of which was labelled with 15N, were co-composted in a ratio of 1: 3 or 3: 1 for nitrogen, and the nitrogen kinetics from cattle feces or (NH4)2SO4 was investigated. In addition, four non-co-composted plots and a chemical fertilizer plot were set up as a control experiment. A 1 : 3 or 3 : 1 mixture of cattle manure and (NH4)2SO4, either of which was labelled with 15N, was applied in the nonco- composted plots. And only (NH4)2SO4 without manure was applied as a nitrogen fertilizer in a plot. In addition to the data on the 1 : 1 co-compost reported in our previous paper (Matsushita et al. 2000: Soil Sci. Plant Nutr., 46, 355–363), the characteristics of these co-composts as nitrogen fertilizer were estimated. The 1 : 3 co-compost was an efficient nitrogen fertilizer for rice plant uptake. The effect was conspicuous, especially in the early period of rice growth. However, inorganic nitrogen was in short supply in the middle period, and became mineralized again in the latter period of rice growth. The cocompost may not be suitable as a slow-acting fertilizer but could be efficient as a quick-acting fertilizer, in terms of organic matter content. When cattle feces and (NH4)2SO4 were co-composted in a ratio of 3 : 1, the dry weight of the rice plants in the co-composted plots was significantly lower than that in the non-co-composted plots on August 12 and afterwards. The least active growth was associated with a shortage of inorganic nitrogen. Especially, the N-uptake ratio by rice plants from (NH4)2SO4 in the 3 : 1 co-compost decreased by about 40% of the value in the non-co-composted plot. The results suggested that (NH4)2SO4 was actively assimilated during the co-composting period in the 3 : 1 co-compost. The co-compost may not satisfy the plant requirement for nitrogen. In contrast, this co-compost could be efficient as an amendment material for soil with a low nutrient content, because the N -residual ratios in soil from (NH4)2SO4 were about 80%. On the other hand, the N-uptake ratio from (NH4)2SO4 with cattle manure in the non-co-composted plot was lower than that without cattle manure in the early period, compared with that in the latter period of rice growth. The results indicated that the slow acting ability of nitrogen from (NH4)2SO4 increased by the addition of cattle manure. Considering the nitrogen loss through the composting process, the N -uptake ratios from cattle feces and (NH4)2SO4 were in the order of 1 : 3 non-co-composted plot > 1 : 3 co-composted plot>3 : 1 non-co-composted plot>(NH4)2SO4 only plot>3 : 1 co-composted plot. In summary, the 1 : 3 co-compost made of cattle manure and (NH4)2SO4 may display a Quick acting ability, the 3 : 1 co-compost could increase the soil nitrogen content, and the mixture of cattle manure and (NH4)2SO4 may exhibit a slow acting ability for nitrogen. In taking account of nitrogen utilization, the simultaneous application of cattle manure and (NH4)2SO4 without co-composting appears to be an efficient method compared with the co-composting method.

Fate of N and Relative Efficiency of 15N-labeled organic materials applied to transplanted rice in Northern Kyushu region of Japan

Abstract Seven kinds of 15N-labeled organic materials were applied to transplanted rice to investigate their N fate and relative efficiency in the northern Kyushu region of Japan. The 15N labeled organic materials examined in a micro-plot experiment were cattle manure compost, poultry manure compost, swine feces, rice straw compost, rice bran, rice straw, and wheat straw. Regarding swine feces, rice bran, and wheat straw, the direct evaluation of their N fate in paddy fields using 15N organic materials has not been reported. A significant difference in the N fate in response to the type of organic materials was observed in the uptake rate by rice plants. The uptake rate at the maturity stage was significantly higher in poultry manure (29% ), swine feces (25% ), and rice bran (26%) than for the other organic materials (6–13%). Cattle manure compost showed the lowest value, namely 6–7%. Using the uptake rate of e5NH4 ) 2S04 observed earlier, the relative efficiency of organic materials (relative uptake rate of organic material N to chemical fertilizer N) was calculated as the index of the organic material N efficiency. These relative efficiencies of organic materials derived from animal wastes were 16–19, 81, 72, and 71% for cattle manure compost, poultry manure compost, poultry manure compost without inherent NH4-N, and swine feces, respectively, and were similar to those estimated by indirect way. The relative efficiencies of organic materials derived from plant residues were 25–31, 73, 33, and 34% for rice straw compost, rice bran, rice straw, and wheat straw, respectively. The N uptake from the organic materials (OM-N uptake) in swine feces and cattle manure compost continued throughout the rice growth period, whereas the OM-N uptake of the other organic materials declined remarkably after 54 DAT. No significant difference was observed in the residual rate and the loss rate among the organic materials. However, some tendencies that might be related to the properties of the organic materials could be revealed, such as the high residual rate of rice straw compost and the high loss rate of cattle manure compost and rice straw.

Changes in the N Recovery Process from 15N-Labeled Swine Manure Compost and Rice Bran in Direct-Seeded Rice by Simultaneous Application of Cattle Manure Compost

The N recovery from 15N-labeled swine manure compost and rice bran with or without simultaneous application of unlabeled cattle manure compost was examined in a paddy field with direct-seeded rice during a 1-year period (1 crop season). In all the 15N-labeled materials including (15NH4)2SO4, the processes of N recovery from the 15N materials by rice plants were different between the plots with and without application of cattle manure compost. At the tillering stage, the N recovery rates from the 15N materials in the plots with application of cattle manure compost were significantly lower than those in the plots without application of cattle manure compost. These recovery rates, however, became close and no significant differences were observed at the maturity stage. Thus, simultaneous application of cattle manure compost could impede the N recovery from swine manure compost, rice bran as well as (NH4)2SO4.

Uptake of carbon and nitrogen through roots of rice and corn plants, grown in soils treated with 13C and 15N dual-labeled cattle manure compost

Abstract Nitrogen and carbon dynamics in paddy and upland soils for rice cultivation and in upland soil for corn cultivation was investigated by using 13C and 15N dual-labeled cattle manure compost (CMC). In a soil with low fertility, paddy and upland rice took up carbon and nitrogen from the CMC at rates ranging from 0.685 to 1.051% of C and 17.6–34.6% of N applied. The 13C concentration was much higher in the roots than in the plant top, whereas the 15N concentration differed slightly between them, indicating that organic carbon taken up preferentially accumulated in roots. The 13C recovery in the plant top tended to be higher in upland soil than in paddy soil, whereas 15N applied was recovered at the same level in both paddy and upland soils. In the experiment with organic farming soil, paddy rice took up C and N from the CMC along with plant growth and the final recovery rates of 13C and 15N were 2.16 and 17.2% of C and N applied. In the corn experiment, a very large amount of carbon from the CMC was absorbed, accounting for at least 7 times value for rice. The final uptake rates of 13C and 15N reached about 13 and 10% of C and N applied, respectively. Carbon emission from the CMC sharply increased by 2 weeks after transplanting and the nitrogen emission was very low. It is concluded that rice and corn can take up an appreciable level of carbon and nitrogen from the CMC through roots.

Using different versions of the Rothamsted Carbon model to simulate soil carbon in long-term experimental plots subjected to paddy–upland rotation in Japan

We validated the Rothamsted Carbon (RothC) model against 14 experimental plots subjected to different paddy–upland rotation patterns, including continuous paddy rice cropping and different periods (short, medium, and long term) of upland conversion, in Akita prefecture, northern Japan. We ran the model using the original version of the RothC model, the paddy-soil version of the RothC model (which uses a reduced carbon decomposition rate), and alternating the use of the original and the paddy-soil versions for years with summer upland cropping and paddy rice cropping, respectively. The best simulation pattern was provided by the alternate use of the two versions. In comparison with the original RothC model, alternate use of the two versions showed a smaller root mean square error in all experimental plots and a smaller absolute value of the mean difference in 10 plots with continuous paddy rice cropping and short- and medium-term upland conversion. Alternate use of the two versions had a lower root mean square error and lower absolute value of the mean difference in long-term upland conversion plots compared to the values for the paddy-soil version and showed better performance than the paddy-soil version when straw was applied. The model performance from alternating use of the two versions compared well with the performance reported in previous studies. Alternating the use of the two model versions provides a good technique for simulating changes in soil organic carbon with time, even with a paddy–upland rotation pattern. In addition, this technique will enable a more accurate inventory of Japanese greenhouse gases and help land managers better manage soil fertility in a paddy–upland rotation system.

Fate of nitrogen derived from 15N-labeled cattle manure compost applied to a paddy field in the cool climate region of Japan

Abstract To estimate the fate of nitrogen (N) derived from cattle manure compost with sawdust (CMC) in a paddy field in the cool climate region of Japan, well-composted 15N-labeled CMC was applied to a microplot field experiment. Throughout the experimental period of three crop seasons, N from CMC was taken up by rice plants without a marked decline. The percentages of N taken up derived from CMC to applied N as CMC (%CNRp) were 2–3% for each year. The N from CMC was taken up by rice plants over the entire growth period by 1–2, 2 and 2–3% as %CNRp at the panicle initiation, heading and maturity stages, respectively. A significant positive linear correlation was found between the cumulative compost N uptake and the number of days transformed to standard temperature (25°C) over the entire experimental period, including the fallow season. The %CNRp was identical at CMC application rates ranging from 1 to 4 kg m−2. Using 15N-labeled CMC, the results showed that well-composted CMC was a stable N source for rice plants for at least 3 years, regardless of the CMC application rate (ranging from 1 to 4 kg m−2) in the cool climate region of Japan. The distribution of CMC N was 7% in the rice plants accumulated over 3 years, 66–69% in the soil and 24–27% was un-recovered at the end of the third crop season.

Inhibitory effects of aromatic acids on nitrogen uptake and transport in rice (Oryza sativa L.) plants cultured on hydroponics

Absrtact The application of fresh wheat or barley straw often inhibits the growth and N uptake of paddy rice plants in the establishment phase. This inhibition is mainly attributed to the deficiency of available N in soil, resulting from a large N assimilation by soil microbes in soils supplied with straw (Rao and Mikkelsen 1976). In a previous report (Tanaka and Nishida 1996), we showed that the activity of 15N uptake from 15NH4 + introduced into the soil decreased by straw application. We found the accumulation of some aromatic acids in soils to levels inhibitory to root elongation when fresh wheat straw was applied (Tanaka 1990; Tanaka et al. 1990). No attempt were made to investigate the effects of aromatic acids on N uptake by rice seedlings. Here we report on examination on whether aromatic acids such as 2-phenylpropanoic acid (2P), 3-phenylpropanoic acid (3P), and benzoic acid (BA), found in paddy soils, may inhibit N uptake and transport in rice plants.

Inhibition of nitrogen uptake by rice after wheat straw application determined by tracer NH4+-15N

Abstract This experiment was carried out to determine whether the delay in rice growth associated with wheat straw application, especially at the early stage, was due to the acceleration of N assimilation or N uptake inhibition. Tracer 15N was used for rice plants cultivated in pots. After 24 h of tracer application the plants and soils were sampled for analysis. Seventeen days after transplanting, N uptake of rice decreased and the amount of unavailable tracer remaining in soil increased by wheat straw application. At the booting stage, 6 d before heading, N uptake was larger and the amount of remaining tracer was lower in the plots in which wheat straw was applied than in the control. It was obvious that the decrease of N uptake by wheat straw application was caused by N uptake inhibition and not by N starvation for a period of time at the early stage. The inhibition was removed at the booting stage.