Crop Report – Week of July 1, 2024

Nodulation and Nitrogen Use in Dry Beans

In late June, adzuki beans that had been in the ground for 3 weeks already had a few nodules on the roots (Figure 1), and the nodules were active (pink inside when split open). Another field of adzuki planted in the same region around the same time did not have any nodules on the roots, and neither did local black beans at a similar growth stage. Inoculants were not used on any of the fields. One key difference is that the adzuki beans with nodules had not yet received any nitrogen fertilizer. This scenario raises questions about nitrogen use in dry beans, given they are legumes that can convert atmospheric nitrogen into ammonium in the soil.

Figure 1. Adzuki beans with nodules (shown with red arrows) on June 25, 2024.

Why do some dry bean fields nodulate earlier, or nodulate more?

Nodulation begins about 14 days after bean emergence but could take 3 or 4 weeks depending on conditions. Nodulation generally reaches its maximum during early to mid-flowering. Phosphorous is required for rhizobia to form nodules and fix nitrogen, and phosphorous deficiency can limit fixation. Potassium and sulphur also play a role, as do soil moisture and other abiotic stresses.

In a study conducted by Dr. Peter Pauls and his research team at University of Guelph, addition of nitrogen fertilizer delayed nodulation, which is a well-documented response. It takes less energy to use soil available nitrogen than to fix atmospheric nitrogen. In the study Pauls applied 90 pounds of nitrogen per acre and it delayed flowering and maturity but it increased yield.

Would use of inoculants improve nitrogen fixation and decrease the need for fertilizer?

Inoculants for dry beans are not widely available in Ontario and are not being used. Studies conducted by Dr. Peter Pauls have shown that inoculation had little to no effect on yield and amount of nitrogen fixation, which agrees with numerous other studies. Plants genetics have a strong influence on yield and ability to fix nitrogen.

Nodulation of dry beans can occur with numerous different species of rhizobia. The bean variety being grown also influences if, or how well, the rhizobia species functions. Where nodulation is occurring without inoculants, there must be native species associating with plant roots.

How much nitrogen is recommended for dry beans?

Dry beans are widely described as poor nitrogen fixers. Many pulses are grown in Saskatchewan, and their ministry of agriculture ranks their pulses in ability to fix nitrogen as follows: faba bean > pea > chickling vetch > chickpea > lentil > soybean > lupin> dry bean.

In an Ontario study, Dr. Peter Pauls grew 23 heirloom and 19 conventional dry bean (Phaseolus vulgaris) varieties in soils with low nitrogen levels. Between 21 and 76% of the nitrogen in the harvested beans was derived from atmospheric nitrogen. If beans cannot fix all the nitrogen they need, there is value in applying nitrogen to crop. Adzuki bean (Vigna angularis) are a different species than the other dry beans (Phaseolus vulgaris) grown in Ontario. Oregon State University research estimates adzuki can only obtain half their required nitrogen through fixation.

At the Huron Research Station, Chris Gillard found that only cranberry bean yields responded positively to added nitrogen, while white and kidney did not. Alberta Pulse Growers recommend about 100 pounds of nitrogen per acre, while 30 years of research in North Dakota indicate about 40 pounds of nitrogen per acre should be applied to inoculated fields and 70 pounds per acre to uninoculated fields minus the soil test nitrate and N credit from the previous crop. Trials conducted in 2019 to 2020 by Michigan State University (MSU) on black, white and small red beans resulted in no significant difference in yield at rates ranging from 0 to 150 pounds of nitrogen per acre, but plant biomass and white mould increased with higher rates of nitrogen. Nitrogen rates above 30 pounds per acre also resulted in fewer nodules on plant roots. However, MSU still recommend applying 40 to 60 pounds of nitrogen per acre.

In recent years, Manitoba Pulse and Soybean Growers (MPSG) have been conducting extensive fertility trials at research stations, as well as on farms, to develop improved recommendations. Their observation from small plot research is that maximum dry bean yield was achieved at the lowest rate of applied nitrogen (35 pounds per acre) and in on-farm trials yield has not been increased by any nitrogen rate tested so far. MPSG guidelines state that producers can expect 86-93% of maximum yield without nitrogen or inoculant applied, and that if producers feel zero nitrogen is too risky, they should apply 35 pounds per acre.

In Ontario, most dry bean producers apply between 40 and 70 pounds of actual nitrogen per acre at planting. In a survey conducted by Ontario Bean Growers in 2021, completed by 55 producers, the majority said they apply liquid or dry nitrogen ahead of planting while about 25% said they apply nitrogen in a 2×2 band at seeding time. A small percentage of respondents apply nitrogen sometime during the growing season.

Weather Summary: Thursday June 27 to Wednesday July 3, 2024

Location	Highest Temp (°C)	Lowest Temp (°C)	Rain for Week (mm)	Rain Since April 1st (mm)	GDD0C April 1st	GDD5C April 1st	CHU May 1st
HARROW
2024	29.1	10.2	14.0	258.5	1543	1076	1462
2023	27.4	13.9	32.3	206.7	1339	885	1245
2022	31.1	9.2	0.9	208.9	1386	950	1383
10 YR Norm (11-20)	27.7	16.6	18.6	291.9	1382	913	1385
RIDGETOWN
2024	30.1	7.4	25.7	339.8	1449	985	1370
2023	29.3	11.9	107.0	294.1	1268	822	1154
2022	31.2	6.6	2.4	176.4	1293	864	1265
10 YR Norm (11-20)	27.9	14.4	11.8	240.2	1292	827	1285
SARNIA
2024	30.5	9.2	13.5	218.1	1428	967	1323
2023	30.2	12.3	16.0	188.2	1222	778	1072
2022	31.7	8.5	1.4	157.1	1268	845	1201
10 YR Norm (11-20)	27.6	14.4	9.6	266.3	1244	782	1220
LONDON
2024	29.0	8.4	29.8	301.4	1424	959	1353
2023	29.0	8.1	35.7	275.6	1267	823	1160
2022	29.8	6.6	8.6	187.5	1247	827	1221
10 YR Norm (11-20)	27.7	14.0	10.6	267.4	1269	808	1264
BRANTFORD
2024	29.2	8.7	18.7	244.6	1367	907	1305
2023	29.7	9.4	67.8	250.4	1257	811	1155
2022	31.4	7.4	4.2	179.2	1249	818	1188
WELLAND
2024	28.8	10.2	28.4	307.0	1424	959	1370
2023	27.7	10.7	78.6	244.1	1256	804	1137
2022	29.3	10.7	1.2	190.6	1292	853	1260
10 YR Norm (11-20)	27.7	15.3	12.0	271.6	1271	809	1263
GODERICH
2024	26.2	6.6	2.7	200.6	1277	820	1186
2023	26.6	7.0	6.7	139.2	1146	718	1020
2022	30.3	7.4	7.5	147.6	1161	743	1100
10 YR Norm (11-20)	25.5	12.6	7.2	231.4	1133	682	1104
ELORA
2024	27.1	8.2	7.7	259.7	1272	820	1217
2023	27.5	7.4	18.1	174.3	1160	730	1060
2022	28.9	7.0	3.7	166.5	1143	724	1085
10 YR Norm (11-20)	26.3	11.6	17.8	266.8	1127	679	1111
MOUNT FOREST
2024	26.7	8.0	5.1	243.1	1257	807	1200
2023	27.7	7.6	1.6	223.7	1158	732	1056
2022	29.5	7.1	8.4	187.2	1143	731	1099
10 YR Norm (11-20)	26.3	11.7	9.4	262.4	1110	670	1104
BARRIE
2024	27.4	7.0	8.8	389.3	1214	763	1170
2023	27.6	8.6	17.0	257.6	1137	705	1037
2022	27.0	7.9	3.3	209.2	1120	699	1081
10 YR Norm (11-20)	26.7	12.7	7.7	248.3	1089	650	1079
PETERBOROUGH
2024	27.8	5.6	19.7	294.4	1245	791	1184
2023	28.4	8.5	9.5	192.8	1168	727	1041
2022	27.6	6.7	0.6	211.9	1153	721	1113
10 YR Norm (11-20)	27.7	12.2	11.1	249.6	1143	694	1119
KEMPTVILLE
2024	28.3	6.2	16.2	304.7	1314	861	1284
2023	29.5	13.4	1.9	231.1	1233	797	1107
2022	27.7	10.9	5.2	303.6	1240	790	1203
10 YR Norm (11-20)	28.9	14.1	24.1	262.0	1200	752	1193
SUDBURY
2024	25.7	8.2	31.5	358.5	1103	675	1078
2023	30.6	7.3	22.3	300.2	1065	672	1003
2022	23.8	8.0	6.2	195.0	1015	623	1016
10 YR Norm (11-20)	27.6	12.3	15.5	238.5	992	604	1022
EARLTON
2024	26.9	6.6	52.2	324.9	1095	674	1082
2023	31.8	5.4	9.5	199.7	1051	656	995
2022	25.1	6.6	11.3	190.6	1019	636	1037
10 YR Norm (11-20)	26.6	11.3	13.0	215.1	915	549	952
SAULT STE MARIE
2024	21.6	7.1	60.4	352.2	1009	568	914
2023	26.3	7.3	19.6	186.9	1023	627	931
2022	21.1	6.3	25.7	236.8	850	460	765
10 YR Norm (11-20)	26.1	9.7	9.8	241.9	873	486	846
THUNDER BAY
2024	26.3	4.9	27.8	246.0	912	493	831
2023	28.3	9.2	19.5	176.4	925	553	913
2022	30.6	3.6	3.6	343.7	814	458	793
10 YR Norm (11-20)	26.1	9.9	29.5	246.4	836	459	825
FORT FRANCES
2024	25.9	3.2	61.1	308.6	974	545	921
2023	29.7	10.5	18.8	154.3	1108	729	1142
2022	26.3	2.4	4.0	377.2	868	515	895
10 YR Norm (11-20)	28.4	9.4	17.5	233.4	953	557	972