Discussion - Agro-ecological Evaluation of Intensive Cropping Systems of Leafy Vegetables for S

fields equally showed a reasonable balance except for calcium and magnesium with high positive balances. These partial balances indicated that there is accumulation of plant nutrients resulting from the intensive use of chemical fertilizers in vegetable production in this area.

was the case of organic manure for farms A, B and C (C:N of 17-28 in 2012) but the quantity applied in C was very small compared to others. For AFC, the C:N was lower in 2012 and higher in 2013 (Table 3-1). The difference in the C:N ratio of AFC manure is related to the source and this contributed to the high organic matter of the soils which is a typical characteristic of Andosols (Kimble et al., 2000; Maeda et al., 2003). In 2013, manure applied was bought from outside the farm and in 2012, manure was obtained from the cattle paddock of the AFC farm. This is opposed to farms A, B and C where the organic manure was collected and gathered outside in an open area. In addition, the source of plant material for organic manure in farms A and B was somehow permanent (plant debris, rice husks and cow manure in exchange for pasture respectively).

INM practices in the selected fields resulted in soil chemical properties similar to values recommended by the Nagano prefecture government (Table 3-2 and 3-3) except for phosphorus. The high phosphorus of these soils was due to the high fixing capacity of the parent soil material (Matsuyama and Saigusa 1994; Shinjo et al., 2006).

3.4.2 Yield and nutrient uptake in response to soil nutrient amendments

Good INM practice ensures optimum yield and high nutrient use efficiency with minimum environmental impacts. INM practices in A, B, C and AFC were similar but differ in the quantity and quality of nutrient-input materials. This resulted to varying nutrient use efficiency and environmental impacts of the farms. Plants take up nutrients in the soil when available but if the amount of readily available nutrients is above the rate of uptake, there will be excess in the soil vulnerable to losses or other chemical and biological processes of the biogeochemical cycles. Yield and nutrient uptake in the four management systems were similar for each crop type indicating that high chemical fertilizer input system did not result to any significant difference in terms of crop yield and nutrient uptake (Table 3-8 and Table 3-9). The excess nutrients applied in the soil resource base were thus vulnerable to other processes including losses and

transformational processes contributing to economic losses of the production systems as well.

Partial nutrient balance analysis indicates that the management system of farm B had the highest positive balances. This means the nutrient use efficiency was lower than in other management systems. In all the assessed systems of vegetable production, calcium and magnesium (for A) showed a high positive balance (Fig 3-11a and b). This is attributable to the application of high amounts of liming material to maintain the pH of the soil within the optimum range that will results to optimum growth of cultivated crop and soil conditions unfavorable for the disease causal agents. Amongst the primary macronutrients, nitrogen was applied in high amount (Mishima, 2001) especially in cropping seasons where Chinese cabbage was cultivated (A) and in the low altitude fields (B) that continuous cropping (double) was the norms (Fig. 3-11 a and b).

Evaluation of the nutrient content of harvested parts and plant residues at harvest in 2012 and 2013 showed that most of the calcium and magnesium taken up by lettuce, cabbage and Chinese cabbage are incorporated back into the system through plant residues (outer leaves) at harvest (Table 3-10 and Table 3-11). Also, high amounts of potassium are also incorporated through plant residues in case of lettuce cultivation only.

The high amounts of calcium and magnesium applied as liming material noticed in 2012 investigated the monitoring of these cations in 2013. The increments of calcium and magnesium in soil and soil solution in A3 and B3 (2013) as illustrated in Fig. 3-5 are attributable to the high content of these nutrients in the easily decomposable residues immediately after harvest.

The harvested yield was highest for Chinese cabbage, followed by cabbage in 2012 and 2013. However, in terms of plant water content, the moisture content of lettuce was higher than that of cabbage (Tables 3-8 and 3-9). However, the plant water content was also dependent on the harvesting period as could be seen on lettuce harvested in 2013

(B3). These results indicate that there is need to identify management practices amongst farmers similar to the INM recommendations of Nagano Prefecture to facilitate the promotion and optimization of nutrient use efficiency and minimal impacts on the environment by intensive production system.

3.4.3 Soil NO₃-N monitoring

Monitoring of NO3-N using the 5TE sensor for two years in intensive vegetable production systems showed results with some differences observed in the four management systems. At the level of the laboratory, the 5TE sensors responded best in NO3-N solution showing a linear relationship between the bulk EC of the sensor and solution NO3-N concentration. This confirmed the strong relationship between ECb and soil solution electrical conductivity (ECw) (Wraith and Das, 1998; Stamatiadis, 1999;

Scudiero et al., 2012). However, laboratory results showed that below certain level of soil moisture content, the 5TE could not detect changes in soil EC, thus NO3-N (Fig. 3-2b). This was ignored in the experiment since the aim of using the 5TE was to monitor changes in soil NO3-N following rainfall that provided soil percolating water when the soil water content was above field capacity.

Soil NO3-N monitored throughout the cropping season showed that NO3-N levels of the top soil layer in the rooting zone of cultivated crops was high at the beginning of the cropping season following chemical fertilizer application and plastic mulching. This is due to the presence of fertilizer that was applied and diluted when the cultivated crops were still at the initial stage of growth and development following transplanting.

In 2012, the sub soil NO3-N was higher than that of the top soil in C3 compared to AFC1 during the initial stage of growth and development. There was rainfall during this stage of growth providing soil percolate water as the carrier medium for both monitored fields but due to the fact that controlled released fertilizers were applied in AFC1, there was no NO3-N readily available during the initial stage of growth. In C3, results indicate

that even before the installation of the 5TE sensors and transplanting, there was already a reasonable leaching of NO3-N elevating the levels of sub soil NO3-N. This continued throughout the cropping season (Fig. 3-4a and b). Contrarily, in AFC1, the top soil NO3 -N started decreasing with active uptake and the sub soil -NO3-N followed the same trend indicating the control release of N from the applied fertilizer that limited the leaching of NO3-N out of the rooting zone (Fig. 3-4a).

In 2013, fields A3 and B3 monitored showed the same trends as C3 in 2012 but in this case the top soil NO3-N levels were higher than the sub soil NO3-N. This was due to the fact that, the fields of 2013 were transplanted earlier and there were very few rainfall events during the initial stage of growth and development when the top soil NO3-N level was high. However, the subsoil NO3-N levels were constantly lower than the top soil NO3-N throughout the cropping season in 2013(A3 and B3) shown on Fig 3-4c and d.

The high NO3-N levels of the sub soil observed in C3 could be attributable to the late planting (June 30^th) coupled with the long period between transplanting and fertilizer application (Fig. 3-4b). In addition, the slope of field C3 could have contributed to the horizontal movements of soil solution containing NO3-N towards the position where the sensors were implanted down slope. Making the soil solution around the sensor higher throughout the cropping season.

NO3-N fluxes in the subsoil layer showed a flush during the initial stage of growth and development, after harvest and before land preparation in April following snow melting (Fig. 3-4a and b). The flush at the beginning of the season is attributed to high amounts of available NO3-N in the rooting zone that is not in synchrony with N uptake by the cultivated crops, thus liable to leaching when the soil moisture content is above the field capacity of the soil. The situation after harvest is caused by the high N content obtained from the readily decomposable plant residues of leafy vegetables.

3.4.4 NO3-N leaching

Estimates of NO3-N leaching showed a good response to fertilizer application in the evaluated farms. High amounts of N were leached in farms where there was high input of chemical N (Table 3-5 and 3-6) and this confirms previous findings that high N input in the form of chemical fertilizers results to high N losses through leaching (Takeuchi, 1997; Molitor, 1998; Kumazawa, 1999; Maeda et al., 2003; Bergstrӧm et al., 2005).

NO3-N leaching from the evaluated fields in 2012 were higher than evaluated amounts in 2013 in the same fields where similar crop type under the same management were cultivated. The difference was as a result of high amounts of soil percolating water resulting from high accumulated rainfall in 2012 compared to 2013. This is in line with the findings of Gheysari et al. (2009) in which NO3-N leaching was assessed in a silage maize field under different irrigation regimes and N fertilizer application rates.

NO3-N leaching in 2013 using the soil N balance estimation systems exposed the capability of the system to evaluate the role of a catch crop initially incorporated a crop rotation (farm A) for the purpose of biological control of pesticide in the farms IPM strategy. This shows the capability of the system to serve as decision support tool in rational fertilizer management in intensive cropping systems which was the original purpose for the development of the model (Sugahara, 2003).

Farm Year pH_1:5

EC (dS m^-1)

Application rate (T ha ^-1)

T-C

(mg kg^-1) NO₃-N NH₄-N T-N P₂O₅ K₂O CaO MgO

2011 7.50 2.48 40 377700 326.50 2.00 20000 91.80 123.30 273.30 71.70

2012 8.00 2.21 40 380900 174.80 0.20 2000 103.50 239.80 66.80 101.70

2011 8.10 2.87 30 193100 309.70 2.60 26000 54.70 136.20 137.10 70.00

2012 7.50 1.37 30 282800 121.50 1.60 16000 84.60 147.00 47.60 100.00

2011 8.00 3.4 10 386700 347.30 13.80 138000 136.60 176.20 535.40 93.80

2012 n/a n/a 0 n/a n/a n/a n/a n/a n/a n/a n/a

2011 6.83 6.23 20 389400 1852.20 21.20 212000 121.10 232.00 133.40 120.00

2012a 8.20 2.46 20 377600 1040.10 4.40 44000 136.40 257.90 67.20 40.00

2012b 7.80 1.77 20 218700 989.10 4.20 42000 135.80 241.00 100.80 40.00

T-C: Total carbon, T-N: Total nitrogen, n/a: no application.

AFC

Macronutrients (mg kg^-1) DW Inorganic N (mg kg^-1)

Organic manure

A B C

Table 3-1 Chemical composition of organic manure applied in selected fields for each farm.

2012a: Samples collected in December 2012, 2012b: Manure samples collected in April 2013.

86 Top soil

2011 2012 2013 2011 2013 2011 2012 2013 2011 2012 2013 2011 2012 2013 2011 2012 2013 2011 2012 2013 2011 2012 2013 2011 2012 2013 2011 2012 2013 A 6.37a 6.27a 6.23a 0.13a 0.27ab 75100ab 53200ab 79900a 5300a 5200a 5200a 6.62a 17.55a 48.94a 0.47a 0.14a 0.12a 1203.71a 1429.16ab 1181.54 782.19a 1087.41a 739.15a 4071.67a 4877.70a 4202.33a 919.44a 789.51a 891.67ab B 6.38a 6.23a 6.10a 0.18aB 0.56aA 59500ab 43700ab 58500ab 4500a 4000a 3900a 20.77a 66.81a 152.03a 0.37a 0.05a 0.44a 1184.95a 1894.67a 1315.34 902.68a 1138.52a 1136.84a 3628.33a 5378.59a 3791.67a 898.61a 749.38a 1044.44a C 6.63a 6.63a 6.67a 0.13a 0.14b 35000b 25300b 34000b 2900a 2700a 2300a 14.34a 7.31a 7.09a 0.31a 0.16a 0.12a 1044.61a 961.54b 867.12 818.34a 852.96a 942.01a 2648.33aB 5985.78aA 2611.00aB 856.94a 734.57a 727.78b AFC 6.60a 6.57a 6.50a 0.08a 0.13b 87300a 55500ab 62600ab 5900a 5200a 3900a 4.50a 10.21a 1.81a 0.42a 0.15a 0.05a 1042.44a 764.44b 711.76 652.66a 1241.85a 686.92a 3430.00a 5062.82a 3115.00a 876.39a 791.36a 752.78ab Sub soil

A 6.43a 6.38a 6.77a 0.16ab 0.13a 61800a 49000a 48500a 4300a 4900a 2900a 12.08a 14.07b 11.23b 787.71a 832.06a 784.7 567.31a 1199.26ab 500.13a 3492.22a 3887.85a 3486.00a 834.72aA 790.12aAB 613.89aB B 6.25a 6.47a 6.57a 0.20a 0.22a 35900a 39600a 26100a 2700a 3900a 1500a 13.28aB 40.32aA 27.31aAB 463.45a 298.73a 914.45 640.61a 528.52b 668.85a 2026.11aB 5743.63aA 1976.33aB 508.33a 776.54a 472.22a C 6.50a 6.50a 6.70a 0.15ab 0.16a 30200a 19200a 26100a 2400a 1900a 1800a 10.17a 10.96b 17.45ab 672.89a 418.45a 678.5 916.74a 1344.81a 956.07a 2080.56a 4554.15a 2100.00a 712.50a 802.47a 552.78a AFC 6.47a 6.60a 6.47a 0.09b 0.13a 40500a 28500a 27200a 2800a 2600a 2000a 3.23a 13.61b 10.34b 496.29a 369.89a 413.25 624.55a 1045.56ab 650.77a 2002.78aB 4740.30aA 1740.67aB 548.61a 776.54a 427.78a

0.14ab 0.22a 0.14ab 0.10b 2012 0.12b 0.30aAB 0.10b 0.09b

NO₃-N NH₄-N P₂O₅ K2O CaO MgO

mg kg^-1 Inorganic N (mg kg^-1) Bray 2 P (mg kg^-1) Exchangeable cations (mg kg^-1)

Time Farm

pH-H₂O EC (dS m^-1) Total C Total N

Tab le 3-2 Mean soil properties of the management systems (A, B, C and AFC) at 0-10 cm (top) and 40-50 cm (sub) depth for fall (at harvest) 2012 and 2013.

Means within a column, followed by a common lowercase letter are not significantly different (P < 0.05, Tukey HSD).

Means along the same row for each property followed by a common uppercase letter are not significantly different (P > 0.05, Tukey HSD).

Tab le 3-3 Mean soil properties of the management systems (A, B, C and AFC) at 0-10 cm (top) and 40-50 cm (sub) depth for April 2012 and 2013.

Means within a column, followed by a common lowercase letter are not significantly different (P < 0.05, Tukey HSD).

Means along the same row for each property followed by a common uppercase letter are not significantly different (P > 0.05, Tukey HSD).

Farm 2012 2013 2012 2013 2012 2013 2012 2013 2012 2013 2012 2013 2012 2013 2012 2013 2012 2013 2012 2013

A 6.42aA 6.52aA 0.10aA 0.09aA 78600aA 80800abA 5000aA 5500aA 20.12aA 6.30aA 0.44aA 0.17aB 4790.33aA 4732.29aA 2006.54aA 1515.91aA 1000.00a 1001.16aA 1551.20aA 1005.13aA B 6.52aA 6.57aA 0.10aA 0.13aA 60500aA 54000abA 4200aA 3800aA 9.86aA 4.32aA 0.38abA 0.16aB 4911.67aA 4219.44aA 1942.26aA 1547.36aA 930.56a 1001.16aA 1731.87aA 1310.68aA C 6.80aA 6.67aA 0.08aA 0.11aA 29700aA 35500bA 2300aA 2700aA 4.77aA 9.77aA 0.34abA 0.14aA 3684.33aA 3441.67aA 1859.91aA 1331.40aA 756.94a 781.25aA 1066.33aA 733.48aA AFC 6.60aA 6.60aA 0.06aA 0.08aA 82000aA 92500aA 5300aA 5900aA 10.55aA 5.13aA 0.23bA 0.15aA 4841.67aA 5118.75aA 1454.19aA 1142.69aA 861.11a 1041.67aA 1069.80aA 920.32aA A 6.53aA 6.58aA 0.09abA 0.17abA 69400aA 41100aA 4200aA 2700aA 11.56aA 37.42aB 519.33aA 4438.19a 1195.09aA 1014.80aA 833.33aA 735.95aA 840.86aA 389.70aA B 6.50aA 6.43aA 0.17aA 0.19aA 31600bA 20600aA 2200abA 1700aA 25.60aA 25.18abA 2375.33bA 2075.69b 1189.06aA 1117.53aA 361.11bA 416.67aA 152.70bA 95.33aA C 6.57aA 6.55aA 0.14abA 0.14abA 25400bA 25600aA 1900bA 2000aA 19.09aA 13.010bA 2881.67bA 2423.26b 1803.68aA 1224.47aA A 500.58aA 383.88abA 148.79aA AFC 6.37aA 6.40aA 0.09bA 0.10bA 41100abA 30600aA 2700abA 2400aA 11.76aA 13.54bA 2501.33bA 2107.29b 1261.37aA 1079.79aA 437.50bA 436.92aA 244.00bA 135.03aA

pH-H₂O EC (dS m^-1) Total C (mg kg^-1) Total N (mg kg^-1)

Inorganic N (mg kg^-1)

Sub soil

Exchangeable bases (mg kg^-1)

Top soil NO3-N NH4-N CaO K2O MgO P2O5

Table 3-4 Correlation with time for total C and N in the top soil layer for each management practice (A, B, C and AFC).

Farm A

Fall 2011

Spring 2012

Fall 2012

Spring 2013

Fall 2013

Fall 2011

Spring 2012

Fall 2012

Spring 2013

Fall 2013 Fall-2011 1.00

Spring-2012 1.00 1.00 Fall-2012 1.00 0.99 1.00 Spring-2013 0.99 1.00 0.98 1.00

Fall-2013 1.00 0.99 1.00 0.98 1.00

Fall-2011 1.00 0.99 1.00 0.99 1.00 1.00 Spring-2012 1.00 0.99 1.00 0.99 1.00 1.00 1.00

Fall-2012 1.00 0.99 1.00 0.98 1.00 1.00 1.00 1.00

Spring-2013 1.00 1.00 0.99 1.00 0.99 1.00 0.99 0.99 1.00

Fall-2013 1.00 0.99 1.00 0.98 1.00 1.00 1.00 1.00 0.99 1.00

Farm B

Fall 2011

Spring 2012

Fall 2012

Spring 2013

Fall 2013

Fall 2011

Spring 2012

Fall 2012

Spring 2013

Fall 2013 Fall-2011 1.00

Spring-2012 0.99 1.00

Fall-2012 0.19 0.04 1.00

Spring-2013 0.97 0.93 0.41 1.00

Fall-2013 0.33 0.47 -0.86 0.11 1.00

Fall-2011 0.99 0.96 0.32 1.00 0.21 1.00

Spring-2012 0.99 1.00 0.08 0.94 0.43 0.97 1.00

Fall-2012 1.00 0.98 0.22 0.98 0.30 0.99 0.99 1.00

Spring-2013 0.83 0.74 0.70 0.93 -0.25 0.90 0.76 0.85 1.00

Fall-2013 0.25 0.38 -0.91 0.02 1.00 0.11 0.35 0.21 -0.34 1.00 Total N (%)

Total C (%)

Total N (%) Total C (%)

Farm C

Fall 2011

Spring 2012

Fall 2012

Spring 2013

Fall 2013

Fall 2011

Spring 2012

Fall 2012

Spring 2013

Fall 2013 Fall-2011 1.00

Spring-2012 0.29 1.00

Fall-2012 0.66 0.91 1.00

Spring-2013 0.27 1.00 0.90 1.00

Fall-2013 0.96 0.54 0.84 0.51 1.00

Fall-2011 1.00 0.25 0.63 0.23 0.95 1.00

Spring-2012 0.29 1.00 0.91 1.00 0.53 0.25 1.00

Fall-2012 0.64 0.92 1.00 0.91 0.82 0.61 0.92 1.00

Spring-2013 0.24 1.00 0.89 1.00 0.49 0.20 1.00 0.90 1.00

Fall-2013 0.96 0.55 0.85 0.53 1.00 0.95 0.55 0.83 0.51 1.00

Farm AFC Fall 2011

Spring 2012

Fall 2012

Spring 2013

Fall 2013

Fall 2011

Spring 2012

Fall 2012

Spring 2013

Fall 2013 Fall-2011 1.00

Spring-2012 0.51 1.00

Fall-2012 0.43 -0.56 1.00

Spring-2013 1.00 0.46 0.48 1.00

Fall-2013 1.00 1.00 1.00 1.00 1.00

Fall-2011 1.00 0.56 0.38 0.99 1.00 1.00

Spring-2012 0.68 0.98 -0.37 0.64 1.00 0.72 1.00

Fall-2012 0.84 -0.04 0.85 0.87 1.00 0.80 0.17 1.00

Spring-2013 0.99 0.63 0.30 0.98 1.00 1.00 0.78 0.75 1.00

Fall-2013 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00

Total N (%) Total C (%)

Values in bold indicates relationship between total C and total N (red); total C versus total C with time (black); total N versus total N (black) exposes the fluctuation of the management practice affecting the soil chemical composition.

Table 3-5 Nitrate-N leaching estimates by the soil nitrogen balance estimation system in 2012.

Field

Cultivated crop

Soil sampling

date

Harvesting date

Fertilizer applied

N uptake (aboveground)

Leached NO3

--N

Soil residual

Soil mineralized

Manure mineralized

Percolate

water Precipitation

A1 L 13-May-12 8-Aug-12 90.0 78.92 32.75 92.05 24.35 25.36 375 598

A2 L 13-May-12 8-Aug-12 90.0 87.07 16.85 37.36 20.89 25.36 375 598

A3 CC 13-May-12 26-Sep-12 340.0 327.15 37.86 74.74 46.60 32.71 480 766

B1 L 13-May-12 3-Sep-12 264.0 104.80 67.15 160.86 27.51 20.19 421 671

B2 L 13-May-12 3-Sep-12 234.0 54.57 72.71 174.19 36.15 20.19 421 671

B3^#2LL L-L 13-May-12 24-Aug-12 356.0 269.53 42.69 118.05 35.66 19.14 379 653

B3^#2LC L-C 13-May-12 25-Sep-12 201.6 165.33 28.24 62.42 46.48 21.80 445 766

C1^#LL L-L 13-May-12 25-Sep-12 87.0 378.79 26.69 58.98 30.88 9.25 445 766

C3 L 13-May-12 3-Sep-12 194.1 76.37 42.79 114.02 23.63 8.52 390 671

AFC1 C 13-May-12 8-Aug-12 150.0 175.53 13.50 37.94 18.64 51.55 375 598

AFC3 C 13-May-12 3-Sep-12 171.0 136.01 41.29 98.91 27.11 57.09 421 671

L: Lettuce, C: Cabbage, CC: Chinese cabbage.

#2: Second crop in the same field.

kg ha^-1 Accummulate water (mm)

Evaluation period

Table 3-6 Nitrate-N leaching estimates by the soil nitrogen balance estimation system in 2013.

Field

Cultivated crop

Fertilizer applied

N uptake (aboveground)

Leached NO3

--N Soil residual

Soil mineralized

Manure mineralized

Percolate

water Precipitation

A1 without Rye in Fall CC 8-Apr-13 4-Jul-13 228.0 303.38 0.00 -41.28 10.14 12.37 141 278

A1 with Rye in Fall CC 8-Apr-13 4-Jul-13 228.0 303.38 8.66 79.38 10.14 12.37 141 278

A2 without Rye in Fall CC 8-Apr-13 15-Aug-13 300.0 396.09 0.00 -36.67 27.21 20.77 186 368

A2 with Rye in Fall CC 8-Apr-13 15-Aug-13 300.0 396.09 9.06 60.53 27.21 20.77 186 368

A3^#2LC L-C 8-Apr-13 17-Sep-13 230.0 216.88 21.98 73.63 48.17 25.44 328 650

B1 L 8-Apr-13 3-Sep-13 306.0 97.39 41.10 223.00 30.35 16.33 237 440

B2 L 8-Apr-13 14-Aug-13 220.0 136.37 17.64 117.91 31.30 13.74 186 368

B3^#2LC L-C 8-Apr-13 18-Sep-13 492.0 444.45 29.53 90.71 48.31 17.43 351 650

C1 L 8-Apr-13 4-Jul-13 201.6 91.39 13.52 115.19 9.32 - 150 278

C2 C 8-Apr-13 4-Sep-13 240.0 277.26 3.36 16.49 30.53 - 242 449

C3 L 8-Apr-13 14-Aug-13 194.1 112.24 15.82 97.97 20.34 - 197 368

AFC2 C 8-Apr-13 31-Jul-13 150.0 250.15 0.00 -46.39 19.28 25.97 196 363

AFC2 with residues of

Flower bean 2012 C 8-Apr-13 31-Jul-13 150.0 250.15 1.70 10.72 19.28 25.97 196 363

AFC3 C 8-Apr-13 4-Sep-13 180.0 188.49 9.49 46.52 30.14 26.58 242 449

L: Lettuce, C: Cabbage, CC: Chinese cabbage.

#2: Second crop in the same field.

Soil sampling date---Harvesting date 2013

Evaluation Period: kg ha^-1 Accumlated water (mm)

Table 3-7 Leaching estimated by the soil N balance estimation system, soil sampling and soil solution in 2012 and 2013.

Field Model Soil samples

Soil

solution Percolation Precipitation

AFC1 13.5 13.99 - 375 598

C3 42.79 32.78 - 390 671

A3 21.98 27.80 36.83 328 650

B3 29.53 24.36 22.10 351 650

2013 2012

NO₃^--N leaching estimates (kg ha^-1) Accumulated water (mm)

92 Table 3-8 Comparison of harvested yield in 2012.

Means within a column, followed by a common lowercase letter are not significantly different (P > 0.05, Tukey HSD).

*Means for harvested and residue are significantly different (P < 0.05, Tukey HSD).

Field^#2 Harvested Residue Total Harvested Residue Total Harvested Residue Lettuce A1 357.70c 398.47bcd 756.17de 15.99de 19.22d 35.20de 95.53abcd 95.16ab Lettuce A2 343.23c 357.90bcd 701.13de 16.86de 21.51cd 38.37de 95.05bcde 94.04abc Lettuce B1 533.70c 447.89bcd 981.59de 16.09de 18.46d 34.55de 96.93ab 95.84abc Lettuce B2 345.90c 271.03cd 616.93e 14.48de 15.79cd 30.27de 95.72abc 94.21abc Lettuce B3 509.75c 337.49bcd 847.24de 30.64cd 21.90d 52.54de 93.97cde 93.50bcd Lettuce (sunny) B3^#2 613.75c 351.14bcd 964.89de 21.11de 12.45d 33.56d 96.59ab 96.43a Lettuce C1 420.86c 261.42d 682.28de 17.02de 14.04d 31.06de 95.95ab 94.61abc Lettuce C1^#2 302.30c 292.54bcd 594.84e 9.50e 10.78d 20.28e 96.84ab 96.23ab Lettuce C3 379.65c 227.03d 606.68e 12.07de 12.21d 24.27de 96.84ab 94.63abc

Mean 422.98 327.21 750.19 17.08 16.26 33.34 95.94 94.90

Cabbage AFC1 1326.77b^* 629.74bc 1956.50c 84.12b^* 57.46ab 141.58bc 93.61e^* 90.82de Cabbage AFC3^※ 538.69c 643.71b 1182.40d 45.04c^* 69.28a 114.32c 91.56f 89.23e Cabbage B3^#2 2077.38a^* 547.54bcd 2624.92b 129.37a^* 42.37bc 171.74a 93.65de 92.04cde

Mean 1314.28 606.99 1921.28 86.18 56.37 142.55 92.94 90.70

Chinese cabbage A3 2442.24a^* 1730.89a 4173.13a 73.01b 72.78a 145.79ab 96.99a 95.56ab

#2 Second crop in a double cropping sequence.

※Experimental field for club-root disease.

Moisture content (%) Fresh weight (g plant^-1) Dry weight (g plant^-1)

93 Table 3-9 Comparison of harvested yield in 2013.

Table 3-9.

Nutrient content (mean) of aboveground biomass in 2012

Means within a column, followed by a common lowercase letter are not significantly different (P > 0.05, Tukey HSD).

*Means for harvested and residue are significantly different (P < 0.05, Tukey HSD).

Field^#2 Harvested Residue Total Harvested Residue Total Harvested Residue

Lettuce A3 521.34d 308.42de 829.75de 17.27d 12.66c 29.93c 96.71a 95.86a

Lettuce B1 417.88d 288.27de 706.15de 15.10d 13.65c 28.74c 96.35ab 95.22ab Lettuce B2 580.57cd 325.22de 905.79cde 23.65cd 17.26c 40.91c 95.92abcd 94.64ab Lettuce B3 723.90cd 379.64de 1103.54cde 19.35cd 14.81c 34.16c 97.28a 96.08a Lettuce C1 521.70d 202.74e 724.44de 20.77d 13.48c 34.25c 96.02abc 93.33bc Lettuce C3 475.94d 182.11e 658.05e 27.15d 15.81c 42.96c 94.29bcd 91.30de

Mean 540.22 281.07 821.29 20.55 14.61 35.16 96.09 94.40

Cabbage C2 1326.83bc^* 501.81cde 1828.63bcd 84.77ab 49.59ab 134.36ab 93.62d 90.10ef Cabbage AFC2 1444.55b 867.46bc 2312.02b 88.74ab 66.78ab 155.52ab 93.87cd 92.32cd Cabbage AFC3^※752.16cd 527.78cde 1279.94bcde 66.40bc 58.13ab 124.53b 90.40e 88.54f Cabbage A3^#2 1354.13bc^* 655.66cd 2009.79bc 77.59ab 54.02ab 131.61ab 94.35bcd 91.77cde Cabbage B3^#2 1422.99b 884.96bc 2307.94b 79.99ab 71.23ab 151.21ab 94.31bcd 91.94cde

Mean 1695.19 886.00 2581.19 87.06 61.80 148.86 94.13 92.15

Chinese cabbageA1 2492.72a^* 1252.97ab 3745.69a 92.05ab 56.32ab 148.37ab 96.25ab 95.47a Chinese cabbageA2 3073.00a^* 1511.33a 4584.33a 119.91a^* 76.51a 196.42a 96.11abc 94.94ab

Mean 2782.86 1382.15 4165.01 105.98 66.41 172.39 96.18 95.20

#2 Second crop in a double cropping sequence.

※Experimental field for club-root disease.

Fresh weight (g plant^-1) Dry weight (g plant^-1) Moisture content (%)

DW Basis Field^#2 Harvested Residue Harvested Residue Harvested Residue Harvested Residue Harvested Residue

Lettuce A1 2.37de 2.76de 1.17cdef 0.95bcd 5.04d^* 8.14ab 0.65e^* 2.29c 0.38abcd^* 0.99ab

Lettuce A2 2.39de 2.76de 1.57b^* 1.05bcd 5.67cd^* 8.70a 0.65e 1.73c 0.37bcd^* 0.61f

Lettuce B1 2.78cd^* 4.05bc 1.05defg 0.77d 6.32cd^* 9.24a 0.65e^* 2.46c 0.37bcd^* 0.97ab

Lettuce B2 1.65e 2.31ef 1.35bcd 1.29ab 5.71cd^* 9.00a 0.70e^* 2.12c 0.28cd^* 0.68ef

Lettuce B3 3.24c 3.77c 1.52bc 1.25abc 7.83ab 9.17a 1.36bcd 2.19c 0.52ab^* 0.75def

Lettuce (sunny) B3^#2 4.05b 3.28cd 1.32bcde 1.21abcd 8.54a 8.66ab 1.41bc 2.29c 0.55a^* 0.76def

Lettuce C1 2.83cd 3.41cd 1.13defg 0.80cd 6.78cd^* 8.90a 0.93de^* 2.99c 0.43d^* 0.93ef

Lettuce C1^#2 4.10b 4.71ab 0.98efg^* 1.55a 5.42bc^* 8.69a 0.88cde^* 2.50c 0.25abc^* 0.66abc

Lettuce C3 3.27c^* 3.93c 0.78g 1.13abcd 6.34cd^* 8.97a 0.78e^* 2.67c 0.39abcd^* 0.84bcd

Mean 2.96 3.44 1.21 1.11 6.41 8.83 0.89 2.36 0.39 0.80

Cabbage AFC1 1.93e 1.84f 0.93fg 1.02bcd 2.75e 2.71c 1.17bcde^* 5.00b 0.35bcd^* 0.92abc

Cabbage AFC3^※ 4.05b 3.90c 1.04defg 1.09abcd 3.15e 2.64c 1.04cde^* 4.79b 0.31abcd^* 1.01a

Cabbage B3^#2 2.71cd 3.30cd 0.90fg 1.11abcd 3.21e 2.71c 1.63ab^* 7.84a 0.48ab^* 1.08a

Mean 2.90 3.01 0.95 1.07 3.04 2.69 1.28 5.89 0.42 1.02

Chinese cabbage A3 5.01a 5.27a 2.61a^* 1.33ab 6.74bc 7.30b 1.97a^* 6.81a 0.55a^* 1.05a

N (%) P₂O₅ (%) K₂O (%) CaO (%) MgO (%)

Means within a column, followed by a common lowercase letter are not significantly different (P > 0.05, Tukey HSD).

*Means for harvested and residue are significantly different (P < 0.05, Tukey HSD).

#2 Second crop in a double cropping sequence.

※Experimental field for club-root disease.

AFC2 C2 AFC2 C2 AFC2 C2 AFC2 C2 AFC2 C2 AFC2 C2

Leaves AFC2 C2 336.86 374.01 0.91 0.98 0.69 0.62 1.66 2.05 6.70 6.52 0.69 0.65

stem 2.96 7.41 371.65 635.53 0.31 0.86 0.22 0.30 4.05 3.39 2.32 1.23 0.57 0.49

Grain 1405.6 875.58 4.73 2.94 1.20 1.30 1.66 2.77 0.21 0.18 0.35 0.42

A1 A2

1.28

0.64 0.52

0.29 Flower bean 2012

61.46

56.37 5.26

4.71 1.89

1.73 6.10

7.24 N

Plant part/Field

Nutrient content (% DW)

Rye Fall 2012

Planting density (plants m^-2)

Aboveground

biomass (g plant ^-1) P2O5 K2O CaO MgO

(g m^-2)

Table 3-10 Nutrient content (mean) of aboveground biomass in 2012.

95 Table 3-11 Nutrient content (mean) of aboveground biomass in 2013.

Means within a column, followed by a common lowercase letter are not significantly different (P > 0.05, Tukey HSD).

*Means for harvested and residue are significantly different (P < 0.05, Tukey HSD.

#2 Second crop in a double cropping sequence.

※Experimental field for club-root disease.

DW Basis Field^#2 Harvested Residue Harvested Residue Harvested Residue Harvested Residue Harvested Residue

Lettuce A3 4.4a 4.65a 1.65c^* 0.87bcd 10.30ab 11.80de 0.57de 1.72d 0.54abc 0.70d

Lettuce B1 4.0ab 4.65a 1.07def^* 0.62de 8.12bcd^* 13.35cd 0.50de 2.51d 0.42cd^* 0.92bcd

Lettuce B2 3.38bc^* 4.36ab 1.24d^* 0.78cde 9.18bc^* 16.26ab 0.26e^* 2.88cd 0.47cd^* 1.00bcd

Lettuce B3 4.3a 4.98a 1.70bc^* 0.99abc 12.164a^* 17.37a 0.57de 2.03d 0.48bcd^* 0.97bcd

Lettuce C1 3.24b 3.64bc 1.5de^* 0.74cde 7.01cde^* 11.67de 0.39e 2.15d 0.36d^* 0.87bcd

Lettuce C3 2.70cde 3.45c 0.71fg 0.72cde 7.68bcd^* 14.61bc 0.37e^* 2.46d 0.44cd^* 0.87bcd

Mean 3.68 4.29 1.25 0.79 9.08 14.18 0.44 2.29 0.45 0.89

Cabbage C2 2.18e 2.64de 0.77efg 0.61def 4.85ef 4.91fg 0.85cd^* 7.20ab 0.43cd^* 1.28bc

Cabbage AFC2 2.48de^* 3.52c 0.84defg 0.69cde 5.67def 6.38f 1.20bc^* 8.12ab 0.53abc^* 1.09bcd

Cabbage AFC3^※ 2.97cd 2.50e 0.65g 0.30f 3.65f 3.49g 0.92cd^* 7.47ab 0.46cd^* 1.77abcd

Cabbage A3^#2 2.74cde 3.3cd 0.84defg 0.63de 5.85def 5.66fg 1.15bc^* 5.49bc 0.43cd 0.80cd

Cabbage B3^#2 2.98cd^* 3.83bc 0.72fg 0.47ef 4.29f 4.59fg 1.37b^* 8.06ab 0.48bcd^* 1.19bc

Mean 2.67 3.16 0.76 0.54 4.86 5.00 1.10 7.27 0.47 1.22

Chinese cabbageA1 4.42a 4.62a 2.24a^* 1.19a 8.03bcd 10.56e 2.24a^* 7.50ab 0.64a^* 1.34ab

Chinese cabbageA2 4.33a 4.99a 2.09ab^* 1.13ab 9.87ab^* 13.69bcd 2.07a^* 8.53a 0.62ab^* 0.98bcd

Mean 4.37 4.81 2.16 1.16 8.95 12.12 2.16 8.02 0.63 1.16

CaO (%) MgO (%)

N (%) P₂O₅ (%) K₂O (%)

0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0

2011-2012 2012-2013 2013

Soil EC1:5

Soil 1:5pH

pH Fall pH Spring EC Fall EC Spring

(b)

0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0

2011-2012 2012-2013 2013

Soil EC1:5

Soil 1:5pH (a) Top

Sub

Fig 3-1 Changes in pH and bulk EC of (a) Top and (b) Sub soil in spring following overwintering of applied manure and at harvest (Fall) in the four vegetable production systems.

y = 95.7x - 0.20 R² = 0.98**

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0 12.0 13.0

0.00 0.03 0.06 0.09 0.12 0.15

Soil NO3-N (DW mg 100g-1)

Sensor EC (dS m^-1)

(a)

Fig. 3-2a Performance test of the 5TE sensor in an NO3-N solution.

** indicates level of significance (P < 0.01).

0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80

Soil water content (m3m-3)/Bulk electrical conductivity (dS m-1) Soil NO3-N (mg 100g-1)

AFC1-Top soil

Soil nitrate-N Sensor bulk EC reading

Sensor soil water content Measured soil water content

0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80

0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40

Soil water content (m3m-3)/Bulk electrical conductivity (dS m-1) Soil NO3-N (mg 100g-1)

AFC1-Sub soil

Soil nitrate-N Sensor bulk EC reading

Sensor soil water content Measured soil water content

0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80

0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00

Soil water content (m3m-3)/Bulk electrical conductivity (dS m-1) Soil NO3-N (mg 100g-1)

C3-Sub soil

Soil nitrate-N Sensor bulk EC reading

Sensor soil water content Measured soil water content 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80

0.00 0.20 0.40 0.60 0.80 1.00 1.20

Soil water content (m3m-3)/Bulk electrical conductivity (dS m-1) Soil NO3-N (mg 100g-1)

C3-Top soil

Soil nitrate-N Sensor bulk EC reading

Sensor soil water content Measured soil water content

Fig. 3-2b Performance test of the 5TE sensor in soil samples continuously wetted with an NO3-N solution.

y = 17.34x - 0.04 R² = 0.85**

y = 24.7x - 1.25 R² = 0.91**

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0

0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40

Soil NO3-N (DW mg 100g-1)

Sensor EC (dS m^-1)

AFC1 ^{Top soil}

Sub soil (a)

y = 7.8x + 0.46 R² = 0.83**

y = 20.4x - 1.9 R² = 0.68**

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0

0.00 0.10 0.20 0.30 0.40 0.50

Soil NO3-N (DW mg 100g-1)

Sensor EC (dS m-¹)

C3 Top soil

Sub soil (a)

Fig. 3-3a Correlation between the soil NO3-N levels and the 5TE sensors bulk EC reading for field monitored in 2012 cropping season.

** indicates level of significance (P < 0.01).

100

y = 36x - 1.4 R² = 0.68*

y = 20.6x - 0.01 R² = 0.86*

0.0 5.0 10.0 15.0 20.0 25.0 30.0

-0.10 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70

Soil NO3-N (DW mg 100g-1)

Sensor EC (dS m^-1)

B3 _{Top soil}

(b)

y = 179.4x - 3.3 R² = 0.77*

0.0 10.0 20.0 30.0 40.0 50.0

0.00 0.05 0.10 0.15 0.20 0.25

Sub soil water NO3-N (mg -1)

Sensor EC (dS m^-1) B3

NO3-N limit in groundwater

(b) y = 45.9x - 1.39

R² = 0.70*

y = 15.2x - 0.01 R² = 0.62**

0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00 18.00 20.00

0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35

Soil NO3-N (DW mg 100g-1)

Sensor EC (dS m^-1)

A3 ^{Top soil}

Sub soil

(b)

y = 251.7x - 5.7 R² = 0.44*

0.0 10.0 20.0 30.0 40.0 50.0 60.0

0.00 0.05 0.10 0.15 0.20 0.25 0.30

Sub soil water NO3-N (mg L-1)

Sensor EC (dS m^-1) A3

NO₃-N limit in groundwater

(b)

Fig. 3-3b Correlation between the 5TE sensor bulk EC reading and soil NO3-N (b), soil solution nitrate-N levels (c) for monitored fields (A3 and B3) in 2013.

*Indicates level of significance (P < 0.05).

101

Soil temperature (o C) Soil moisture content (m3 m-3 ) Soil NO3-N (mg 100g-1 ) Rainfall (mm) Soil solution NO3-N (mg L-1 )

Top soil

Sub soil

0 5 10 15 20 25 30 35

0 0.1 0.2 0.3 0.4 0.5 0.6

0 10 20 30 40 50 60 70 80 90

04/13/12 05/02/12

05/22/12 06/11/12

07/01/12 07/21/12

08/10/12 08/30/12

09/19/12 10/09/12

10/29/12 11/18/12

12/08/12 12/28/12

01/17/13 02/06/13

02/26/13 03/18/13

04/08/13 0

2 4 6 8 10 12 14 16 18 20 22 24

0 10 20 30 40 50 60 70 80

Top soil

Sub soil

Sub soil solution_Sensor

(a) AFC1-

1 2 3 4 ⁵ 6 6

Cabbage

1: Fertilizer application and plastic mulching, 2: Sensor implantation, 3: Transplanting, 4: Harvest, 5: Winter monitoring starts, 6: End of winter monitoring and vertical bars indicate rainfall.

102

1: Fertilizer application and plastic mulching, 2: Sensor implantation, 3: Transplanting, 4: Harvest, 5: Winter monitoring starts, 6: End of winter monitoring and vertical bars indicate rainfall.

5 6 3 4

1 2

(b) C3- Lettuce Top soil

Sub soil

0 5 10 15 20 25 30 35

0 0.1 0.2 0.3 0.4 0.5 0.6

0 10 20 30 40 50 60 70 80 90

04/13/12 05/02/12

05/22/12 06/11/12

07/01/12 07/21/12

08/10/12 08/30/12

09/19/12 10/09/12

10/29/12 11/18/12

12/08/12 12/28/12

01/17/13 02/06/13

02/26/13 03/18/13

04/08/13 0

2 4 6 8 10 12 14 16 18 20 22 24

0 10 20 30 40 50 60 70 80

Top soil

Sub soil

Sub soil solution_Sensor

Soil temperature (o C) Soil moisture content (m3 m-3 ) Soil NO3-N (mg 100g-1 ) Rainfall (mm) Soil solution NO3-N (mg L-1 )

103

1: Fertilizer application and plastic mulching, 2: Sensor implantation, 3: Transplanting, 4: Harvest, 5: Planting of second crop, 6: Harvesting of second crop and vertical bars indicate rainfall.

6 4 5

2 1

Soil temperature (o C) Soil moisture content (m3 m-3 ) Soil NO3-N (mg 100g-1 ) Rainfall

Soil solution NO3-N (mg L-1 )

04/08/13 04/17/13

04/27/13 05/07/13

05/17/13 05/27/13

06/06/13 06/16/13

06/26/13 07/06/13

07/16/13 07/26/13

08/05/13 08/15/13

08/25/13 09/04/13

09/18/13 0

2 4 6 8 10 12 14 16 18 20 22 24

0 10 20 30 40 50 60 70 80

Top soil

Sub soil Sub soil water solution

0 0.1 0.2 0.3 0.4 0.5 0.6

0 10 20 30 40 50 60 70 80 90 100 110 120 130

Top soil

Sub soil

0 5 10 15 20 25 30 35

Lettuce-104

Soil temperature (o C) Soil moisture content (m3 m-3 ) Soil NO3-N (mg 100g-1 ) Rainfall (mm) Soil solution NO3-N (mg L-1 )

(d) B3-

04/08/13 04/17/13

04/27/13 05/07/13

05/17/13 05/27/13

06/06/13 06/16/13

06/26/13 07/06/13

07/16/13 07/26/13

08/05/13 08/15/13

08/25/13 09/04/13

09/18/13 0

2 4 6 8 10 12 14 16 18 20 22 24

0 10 20 30 40 50 60 70 80

Top soil

Sub soil

Sub soil water solution

0 0.1 0.2 0.3 0.4 0.5 0.6

0 10 20 30 40 50 60 70 80 90 100 110 120 130 Top soil

Sub soil

0 5 10 15 20 25 30 35

Lettuce-Cabbage

2 3 4

1: Fertilizer application and plastic mulching, 2: Sensor implantation, 3: Transplanting, 4: Harvest, 5: Planting of second crop, 6: Harvesting of second crop and vertical bars indicate rainfall.

Fig. 3-4a, b, c, d. Trends of NO3-N leaching on daily basis as a function of climate (rainfall and temperature) and soil moisture content throughout the cropping season at field level (2012 and 2013).

105

Fig. 3-5 Changes of basic cations in the top soil (a) sub soil (b) layers and sub soil solution (c) in 2013 monitored fields (A3 and B3).

Water samples were not collected on 14^th Aug (A3) and 3^rd Sept (A3 and B3) due to the very low moisture content.

0.0 80.0 160.0 240.0 320.0 400.0